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SQL tutorials 18: SQL Foreign Key Constraint
 
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SQL Tutorial 18: SQL foreign key constraint. Topic covered in this tutorial 1. Defining SQL foreign key using create table at column level 2. Defining SQL foreign key using create table at table level 1. Defining SQL foreign key using Alter Table statement Links Website article: http://www.rebellionrider.com/sql-foreign-key.htm Primary key tutorial: http://www.rebellionrider.com/sql-foreign-key.htm Create Table Tutorial: http://www.rebellionrider.com/sql-create-table.html Tool used in this tutorial is SQL Developer. This tutorial series is part of SQL expert exam certification training. if you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Contacts E-Mail [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. http://in.linkedin.com/in/mannbhardwaj/ Thanks for linking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com Foreign key is an Input/output data constraint which is also known as referential integrity constraint. Foreign key represent a link or say a relationship between columns of tables. Similar to primary key constraint Foreign Key constraint is also of two types. Simple Foreign key constraint and Composite Foreign key constraint. Constraint which involves only one column in foreign key in child table and one column in reference key in parent table is called Simple Foreign Key. While the constraint which involves more than one column in foreign key in child table and more than one column in reference key in the parent table is called Composite Foreign Key.
Views: 96248 Manish Sharma
SQL tutorials 17: SQL Primary Key constraint,  Drop primary Key
 
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Blog link: http://www.rebellionrider.com/sql-primary-key.htm SQL tutorial on Primary key / SQL Primary key, In this tutorial you will learn about simple primary key, composute primary key, how to drop primary key. defining primary key using create table and alter table along with many other things. Tool used in this tutorial is SQL Developer. This tutorial series is part of SQL expert exam certification training. if you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Contacts E-Mail [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. http://in.linkedin.com/in/mannbhardwaj/ Thanks for linking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com So Primary Key There are two types of Primary keys First is Simple primary Key: Primary key which Involves only one column and Second is Composite Primary Key: Primary Key which involves more than one column. We will start with Simple primary key. You can create Primary key either with Create Table statement of by using Alter table Statement. Let's define simple primary key using create table statements. With create table statement we can either define primary key at column level or at table level. We will start with defining Primary key at column level using create table statement. You just have to put keyword Primary key after data type and size of column while defining a column of a table. Here oracle server will create a primary key on product id with default constraint name which will be slightly difficult to understand. You can give your own name to your constraint which is also a good practice.
Views: 93978 Manish Sharma
Oracle SQL Tutorial 18 - How to Create Foreign Keys
 
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In this video we are going to be creating foreign keys. I highly recommend watching the previous video before you watch this one. Essentially, we are creating a very simple database for a system where we can create projects and add people to those projects. We started with the users table: --Delete the table if needed: --DROP TABLE users; CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, CONSTRAINT users_pk PRIMARY KEY (user_id) ); Now we are going to create a table for projects with a column that is a foreign key to the username. We're going to want to make this match data types: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) ) Next, we need to add the column attributes we decided on last video: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL ) NOT NULL because we want every project to have a creator, but we are not labeling UNIQUE because that means we could only have a specific username once in the table. We want to allow a user to create multiple projects. We also need to add a primary key: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (username) ) Now, the question that remains is, how can I tell Oracle that I want the username to reference the username column of the other table? We have to make a foreign key constraint. As you've learned from the previous videos, there are about three ways to create constraints. You can do it inline at the column level, unnamed. You can do it at the column level, named, and you can do it at the Table level, named. Usually the table-level is preferred, but I will quickly remind you how to do all three again. CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL REFERENCES users (username), CONSTRAINT projects_pk PRIMARY KEY (project_id) ) This works, but if we want to name it, we should do this: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL CONSTRAINT projects_users_fk REFERENCES users (username), CONSTRAINT projects_pk PRIMARY KEY (project_id) ) This works, but the preferred method is to do it at the table level: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (project_id), CONSTRAINT projects_users_fk FOREIGN KEY (creator) REFERENCES users (username) ) Great! So you've learned how to create a foreign key, now we can see it inside of Oracle SQL Developer. One important thing when it comes to foreign keys is what happens when have data in your database and you try to delete the parent row that a row in the child table references? In the next video we are going to configure that using ON DELETE. See you all then and if you enjoy this series, please do me a huge favor by liking the video and subscribing to my YouTube channel. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HELP ME! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 16038 Caleb Curry
How to drop Foreign Key Constraints in SQL Server Database for all the tables -  SQL Server  Part 72
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server developer, you are asked to provide the scripts those can be used to drop Foreign Key Constraints on all the tables in a database if exists. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-drop-foreign-key-constraints-in.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 2168 TechBrothersIT
Example on foreign key constraint and delete cascade
 
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Join discussion on http://www.techtud.com/video-illustration/following-table-has-two-attributes-and-c-where-primary-key-and-c-foreign-gate
Views: 6710 Techtud
Oracle Drop, Disable and Enable Constraints تعليم اوراكل
 
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by Mohamed El Desouki - محمد الدسوقى [email protected] Tel :00966 553450836 جامعة سلمان بن عبد العزيز - السعودية - الخرج How to Drop , Disable and Enable Constraints. كيف حذف و تعطيل و إعادة تشغيل القيود Text Book: Fundamentals of Database Systems, 5th Edition, by Elmasri/Navathe, published by Addison-W oracle create table statement oracle drop table statement oracle constraints database constraints primary key constraint foreign key constraint check constraint null not null constraint unique constraint
How to find all database constraints with SQL in Oracle.
 
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I have written a small sql code to find out all database constraints. Just be sure you have dba permission, otherwise you might not view all constraints. To see constraints separately for dba and user you can use user or dba instead of all, like user_constraints or dba_constraints, user_cons_columns, dba_cons_columns. I have used all_ to find out everything instead in a single query.
Views: 815 Subhroneel Ganguly
Oracle Tutorials : 5 - CREATE / DROP TABLE
 
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Oracle Tutorials : 5 - CREATE / DROP TABLE
Views: 803 Meganadha Reddy
How to drop all Default Constraints in SQL Server Database - SQL Server / TSQL Tutorial Part 94
 
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SQL Server / TSQL Tutorial Scenario: You are working as SQL Server Developer, you need to generate scripts to drop all the Default Constraints in SQL Server Database. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/05/how-to-drop-all-default-constraints-in.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 554 TechBrothersIT
MySQL 17 - ON DELETE and ON UPDATE
 
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Now, what happens when you have successfully created a reference, and now you try deleting the parent? This is where the ON DELETE clause come in. This is essentially how we configure how strict a foreign key is. There are 3 options you can give for an ON DELETE: RESTRICT / NO ACTION Yes - In MySQL they are the same, but not all DBMS. CASCADE Yes SET NULL Yes Now the default is RESTRICT. This means that when you try to delete a parent row, MySQL is going to throw an error and not let you. Cascade means that if you delete the parent row, any rows that reference that parent will also be deleted. This is pretty dangerous and not often recommended. SET NULL will set the foreign key to be NULL. Now obviously, this is going to require that the foreign key is not labelled NOT NULL. In addition to the ON DELETE clause, there is the ON UPDATE clause. This one is a little less common because it configures what happens when a parent value changes. Obviously, when you are referencing a primary key, the ON UPDATE clause is nearly useless. That's because the primary key value is never supposed to change. If, on the other hand, we have a foreign key referencing a UNIQUE column that is not a primary key, it may change occasionally. So the only times you have to worry about the ON UPDATE clause is with foreign keys referencing UNIQUE columns that are not a primary key, and when you have natural keys that break the rules and actually do change at some point in time. The ON UPDATE clause has the same options as the ON DELETE clause and they all work the same way. Now, the last thing you need to know about foreign keys is that they must match the data type of the column you are referencing. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 11041 Caleb Curry
Could not drop object because it is referenced by a FOREIGN KEY constraint - SQL Server P74
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server DBA or Developer, You need to drop a table from a database. When you execute drop table SchemaName.TableName statement, you get below error. Msg 3726, Level 16, State 1, Line 12 Could not drop object 'SchemaName.TableName' because it is referenced by a FOREIGN KEY constraint. Now we know that the table is referenced by Foreign Key Constraint. The problem is how to find which table has that Foreign Key Constraint that is referencing to this table. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/could-not-drop-object-because-it-is.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 1991 TechBrothersIT
Oracle 12C Tutorial 20 - Constraints (Primary, Foreign, Unique, Null etc.)
 
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This Video Tutorial Will Describe about various constraints we can use with tables. Some of the constraints can used as table level or column level so also known as table level constraints and column level constraints. These command will also work on other versions of database like Oracle 11g Database, Oracle 10g Database, Oracle 9i Database, Oracle 8i Database, Oracle 8 Database and so on. In this video i explain Not Null Constraint, Unique key Constraint, Primary Key Constraint, Foreign Key - Reference key Constraint, Check constraint and user_constraints table. Full Syntax will be given in this video tutorial about how to use these constraints. Along with live example to execute Not Null Constraint, Unique key Constraint, Primary Key Constraint, Foreign Key - Reference key Constraint, Check constraint and user_constraints table . All the keywords, format, mandatory clauses etc are described in this video.
Oracle SQL Tutorial 15 - How to Add Primary Key Constraints
 
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The goal of this video is to take the CREATE TABLE statement we have and walk through the different ways to create primary keys. This and foreign keys are the most common constraints, so we need to make sure that you have this one down. Once we have a more complex database design with multiple tables, we will learn the proper way to create foreign keys. For now, I am going to keep all of our constraints at the column level, unnamed. The only exception is the primary key, because that is what we are focusing on in this video. The first way to create the primary key is at the column level, unnamed. The primary key is very important because it what we use to distinguish rows from one another. Every table you create is going to need a primary key, and I suggest putting a lot of effort into making sure your keys are set up correctly and organized. --Delete the table if needed: DROP TABLE users; CREATE TABLE users( user_id NUMBER PRIMARY KEY, username VARCHAR2(50 CHAR) NOT NULL UNIQUE ) The next way is at the column level, but named: --Delete the table: DROP TABLE users; CREATE TABLE users( user_id NUMBER CONSTRAINT users_pk PRIMARY KEY, username VARCHAR2(50 CHAR)NOT NULL UNIQUE ) The general naming convention here is the table name followed by an underscore, followed by pk for primary key. Finally, the third way, which is at the table level, is the way we are going to create our primary key: --Delete the table: DROP TABLE users; CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) NOT NULL UNIQUE, CONSTRAINT users_pk PRIMARY KEY (user_id) ) Now, once you've created these constraints, you can use Oracle SQL Developer to find these constraints. Open your databases in the connections tab and find the table in the Tables folder. Double click your table and travel to the Constraints tab. You can tell here that the UNIQUE constraint still exists in this table, but it has a pretty disgusting name. It kind of wants to make me puke. Referencing that constraint in the future with that wacky name would be a burden. Engrave these three options in your head so that you can use any of them whenever you need and can read other peoples' code. Thank you for sticking with the series thus far. In the next video, we will be…doing something. See you then! :) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me on Patreon! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 10934 Caleb Curry
Foreign Key in Oracle
 
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Foreign Key in Oracle oracle foreign key WHAT IS A FOREIGN KEY IN ORACLE? 1)A foreign key is a use to make referential integrity in database. 2)Foreign key values in one table must also appear in another table also. 3)The referenced table is called the parent table. 4)Table with the foreign key is called the child table. 5)The foreign key generally reference a primary key in the parent table. CREATE TABLE DEPT --- parent table ( DEPT_ID NUMERIC(10) NOT NULL, EMP_ID NUMERIC(10) NOT NULL, CONSTRAINT DEP_PK PRIMARY KEY (DEPT_ID) ); CREATE TABLE EMPLOYEE -- child table ( EMP_ID NUMERIC(10) NOT NULL, NAME VARCHAR2(50) NOT NULL, CITY VARCHAR2(50), DEPT_NO NUMERIC(10), CONSTRAINT ID_PK PRIMARY KEY (EMP_ID), CONSTRAINT FK_DEP FOREIGN KEY (DEPT_NO) REFERENCES DEPT(DEPT_ID) ); #techquerypond https://techquerypond.wordpress.com https://twitter.com/techquerypond
Views: 366 Tech Query Pond
Foreign Key (FK) Constraint in SQL Server (Referential Integrity)
 
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Foreign Key (FK) Constraint in SQL Server Check my blog for more on Constraints and related sample SQL Queries: http://sqlwithmanoj.com/2009/12/27/sql-basics-working-with-foreign-key-fk-constraints/ For more updates like my page in FB: https://www.facebook.com/sqlwithmanoj
Views: 11595 SQL with Manoj
How to disable all Foreign Key Constraint in SQL Server Database-SQL Server / TSQL Tutorial Part 77
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server developer, You need to provide the scripts to disable all the Foreign Key Constraint in SQL Server database. This might be scenario where you need to load one time data and you are ok if data violate referential integrity. Link to scripts used in SQL Server / T-SQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-disable-all-foreign-key.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 1235 TechBrothersIT
Oracle SQL Tutorial 6 - Relationships and Primary and Foreign Keys - Database Design Primer 3
 
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HAPPY VALENTINES DAY!!! Let's talk relationships.. This is the 6th video in your Oracle Database series. We are discussing database relationships which are a key feature of relational database management systems. We first discussed entities and attributes. I talked about how each entity is assigned a table and each attribute is a column within a table. We moved on to the three kinds of relationships. The first was one-to-one. This describes an entity and an attribute. A piece of data that is exclusive to an entity is, by definition, an attribute of that entity. This is stored in one table with the attribute being a column within this table. The second relationship is one-to-many. This relationship is between two entities. The way we properly store this in a database is using a foreign key in the child table. Remember, the child table is the entity on the many side of the one-to-many relationship. Every row within the child table will have a value for the foreign key that references a primary key in the parent table. This assumes that the foreign key field is not optional (NOT NULL). If the foreign key is optional, than a reference is not required but any reference must be valid. The third kind of relationship is a many-to-many relationship. In this situation, we need 3 tables. The many-to-many relationship is broken up into two one-to-many relationships. The intermediary table will associate each entity from one table with the appropriate entities in the other table. There is debate as to whether this table needs a primary key. This is because you can intact use the combination of two foreign keys as a primary key. This works because we will never have two duplicate rows within the intermediary table and the two foreign keys work as a compound key because of this. We finally discussed primary keys and foreign keys. Primary keys are used to keep each row inside of a table unique. If this key is a computer generated number it is known as a surrogate key, otherwise it is known as a natural key. Natural keys have real world meaning. For example, a social security number may work, or an email address (in some situations), etc. Whichever type of key you choose is solely up to you and/or the company you may be working for. HELP ME! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://Twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 37505 Caleb Curry
drop primary key,not null,unique,default and check constraints from columns in a table
 
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This video explains how to drop primary key,not null,unique,default and check constraints with or without constraint name in a table link to HOW to add constraint while creating table: https:// https://www.youtube.com/watch?v=dh_UKs-LnK8 link to how to add new columns with constraints : https://www.youtube.com/watch?v=UNAatxnnwB8 link to how to add constraints to existing column https://www.youtube.com/watch?v=02_fXRQpwSc how to drop all constraints on the table: https://www.youtube.com/watch?v=CM7FPqIr6gc subscribe - https://www.youtube.com/channel/UCNl7...
Views: 1650 kwl zerotwonine
SQL in Oracle 11g Tutorial #7: Alter table( Add, Delete , Enable and Disable Primary Key)
 
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SQL in Oracle 11g Tutorial #7: Alter table( Add, Delete , Enable and Disable Primary Key). This video will explain you the following: 1. How to Add the Primary Key 2. How to delete the primary Key 3. How to Enable the Primary Key 4. How to disable the primary key Thanks for Watching my Channel “Learn TechToTech”. Please subscribe my channel for getting first updates after uploading video.Social Media pages of Channel are: 1. My Website : www.learnfromrakesh.com 2. My Twitter: https://twitter.com/LearnTechtotech 3. Facebook Page: https://www.facebook.com/LearnTechToTech 4. Blogger : https://learntechtotech.blogspot.in/ 5. Google+ : https://learntechtotech.blogspot.in/ 6. Pinterest : https://in.pinterest.com/LearnTechToTech/ 7. LinkedIn: https://www.linkedin.com/in/Learntechtotech/ Playlist of Different Technology: 1. Operating System : https://goo.gl/q6SfrW 2. Python Programming Language : https://goo.gl/L8b5dc 3. C Language : https://goo.gl/SwvDu9 4. C language for Placement: https://goo.gl/AaQBa4 5. Java: https://goo.gl/M8F2uy 6. MySql : https://goo.gl/vdJbHQ 7. Android Mobile Application Development: https://goo.gl/M6woaT 8. Kotlin Programming Language : https://goo.gl/GXE5cd 9. Go Programming: https://goo.gl/Ua3xYW 10. Internet of Things(IoT): https://goo.gl/f2afkY 11. Oracle 11g : https://goo.gl/zds8r2 12. C++ : https://goo.gl/C1psMT
Views: 195 Learn TechToTech
Oracle SQL Tutorial 13 - How to Add Column Constraints (Attributes)
 
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So far, we have this table declaration: CREATE TABLE users( user_id NUMBER, username VARCHAR(50 CHAR) first_name VARCHAR2(50 CHAR), last_name VARCHAR2(50 CHAR) ) We can run this command see that it works. As we are learning though, we are going to want to be able to recreate our table with different settings and such, but if you try to run this command, it will complain that the table already exists. So we first need to delete this table before we start editing settings. When we get more experienced, we will learn about ways to edit the structure of a table that already exists. To fix this, we can get rid of the table using the DROP TABLE command: DROP TABLE users You can run this every time if you need to practice by adding a semicolon after it. This is how you can tell Oracle that you are putting in another command after it. This is known as a delimiter. When you run the script, it is going to run both commands. Now we can go through and reconsider our table structure. This is fine for starting out because we don't have any important data in our database, but once your database is in production you are not going to want to just drop tables. In the last video we discussed different constraints that you can apply to columns in a database table, but how do you actually apply these when you are creating a table? The first way you define constraints is to put them right after the column in your CREATE TABLE statement. CREATE TABLE users( username VARCHAR2(50 CHAR) NOT NULL ) When we define constraints this way, we usually say we are adding column attributes. If you have two constraints you want to add, you just put one after the other with spaces in between. There is no particular order that is required. CREATE TABLE users( username VARCHAR2(50 CHAR) NOT NULL UNIQUE ) In this situation we have already given the column the NOT NULL and UNIQUE attributes, so we should consider making this a primary key: CREATE TABLE users( username VARCHAR2(50 CHAR) PRIMARY KEY ) As you can see, adding column attributes is super easy. We can add a default like this: CREATE TABLE users( username VARCHAR2(50 CHAR) PRIMARY KEY, account_balance NUMBER DEFAULT 0 ) Note that now we need the comma after the first row. There are a few constraints we did not talk go through an example, specifically foreign keys and check constraints. We will be adding these constraints to our database in future videos. In the mean time, I have a thought for you… Many people prefer to name their column constraints. That way, we can refer to certain constraints by name. For example, we might have a primary key constraint that could be named users_pk. The way we are creating these constraints does not allow for this feature, so in the next video we are going to be discussing different ways to create constraints. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me on Patreon! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 14928 Caleb Curry
How to Generate Drop Table Statement for all the tables in a database - SQL Server Tutorial Part 48
 
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SQL Server / TSQL Tutorial Scenario: How to Generate Drop Table Statement for all the tables in a database You are working as SQL Server developer in Credit Card Company. You need to generate Drop Table statements for all the tables in Database TechBrothersIT that you are using as Staging for Data Loading process. How would you do that? Link to scripts used in the video http://www.techbrothersit.com/2016/02/how-to-generate-drop-table-statement.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 1844 TechBrothersIT
Oracle SQL Tutorial 19 - ON DELETE (SET NULL and CASCADE)
 
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Welcome everyone! Something you need to consider when you are creating foreign keys is what happens if you delete the parent? As a reminder, the parent is the row that has the value you are referencing in the row that has a foreign key. Why is this something important to consider? It's important because foreign keys need to protect us from two primary things, unacceptable INSERT statements, and unacceptable DELETE statements. Let's see what happens when we try to insert incorrect data into the table with the foreign key: INSERT INTO projects VALUES (1, 'Update website homepage', 'CalebCurry') The response tells us plainly that there is no such user in the users table. So this works correctly. Deleting data on the other hand works a bit differently because the database does not know what you want to do with the child row when you delete the parent from the parent table. By default, we will get an error message that prevents the parent from being deleted, but there are some other options. How do we configure this? This is where the ON DELETE statement comes in. We add the keywords ON DELETE right after the foreign key and then we can give it the option of CASCADE or SET NULL. CASCADE means that if we delete the parent, we are also going to delete the child. In our situation what that means is that if somebody creates a project in our project table and then that persons account gets deleted, all of the projects he owns will also be deleted. CASCADE: CREATE TABLE projects( project_id NUMBER, Project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (project_id), CONSTRAINT projects_users_fk FOREIGN KEY (creator) REFERENCES users (username) ON DELETE CASCADE ) SET NULL will take the value in the child table and get rid of it. What you are left with is NULL. This means that we have an orphaned child. The first thought you might have is that it is a bad thing to have an orphaned child, but in databases that is not always so. In our application if we had it set to SET NULL, when a user account gets deleted the projects would remain in existence they would just lack a creator. This might be a good thing if you are concerned about the long term survival of a project, this might be the route you want to go. It ultimately depends on the application purpose. If you don't like CASCADE or SET NULL, you can leave the entire ON DELETE statement and just have Oracle throw an error when a parent is deleted. As for us, we are going to use ON DELETE CASCADE. We need to use this with extreme caution. If you are not careful, someday you will run a delete a row and that will cascade through you database deleting a bunch of stuff you didn't want to delete. Stuff happens, so make sure you back up your database every once in eternity. Now, in the last video we started with a database design that had three tables. We've only created two in this video. In the next video we are going to create the next one, which is a little special. Then we'll finish things up by adding some indexes. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me on Patreon! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 11427 Caleb Curry
Oracle SQL Tutorial 12 - Intro to Constraints
 
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As I believe I've mentioned in an earlier video, a constraint is basically a rule we can put in our database that prevents someone from putting the wrong data in. It protects our relationships and data integrity. Because the goal of these constraints are to protect our data integrity, you may hear them called integrity constraints. There are many integrity constraints we are going to talk about: NOT NULL UNIQUE PRIMARY KEY FOREIGN KRY CHECK There is also the DEFAULT attribute. These are all keywords we can add to our columns that will change the way the database works with our data and also prevents incorrect data. NOT NULL is a constraint you can put on a column that prevents nulls. A null is the absence of a value. When we say null, we are saying that every single row has to have a value for this column. UNIQUE is a constraint that makes every row have a unique value for this column. Now note, this does not require values to be put it, and it will allow multiple rows to be null. Next, we are going to talk about primary keys. What qualifies a column as a candidate key? First, not a single row should have a null for that column. Second, every row must be unique. The primary key constraint is essentially a combination of the NOT NULL constraint and the UNIQUE constraint. The foreign key constraint sets the requirement that any value in this column for any row must match a row in another column. Check constraints allow us to be more strict with what data is allowed in our database. NOT NULL and UNIQUE give some level of restriction, but what if we want something more specific? For example, what if we only want values between 0 and 100? That is where check constraints come in. When using check constraints, you give a boolean expression. A boolean expression is something that can be evaluated to true or false. It will only insert the row if the value you try to put into the row makes the expression evaluate to true. So if you put in a value too great or small, the expression will be false and the data is not allowed to be entered. The default constraint is a value you can give a column, and if for any reason when the row is created in the table a value is not provided, the default value will be given. So for example, we could have a bank account table where the balance defaults to 0. How do you actually implement these constraints when you are creating a table? In the next video we are going to be adding these to our users table. Please be sure to subscribe! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me on Patreon: http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 15182 Caleb Curry
Oracle SQL Tutorial 21 - How to Create / Drop Indexes
 
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In the last video, we wrote up the SQL to create three tables: CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, CONSTRAINT users_pk PRIMARY KEY (user_id) ); CREATE TABLE projects( project_id NUMBER, Project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (project_id), CONSTRAINT projects_users_fk FOREIGN KEY (creator) REFERENCES users (username) ON DELETE CASCADE ); CREATE TABLE project_users( project_id NUMBER NOT NULL REFERENCES projects (project_id) ON DELETE CASCADE, user_id NUMBER NOT NULL REFERENCES users (user_id) ON DELETE CASCADE, CONSTRAINT project_users_pk PRIMARY KEY (project_id, user_id) ); I'm going to increase the size of the users table a bit by adding a first and last name column. CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, first_name VARCHAR2(50 CHAR), last_name VARCHAR2 (50 CHAR), CONSTRAINT users_pk PRIMARY KEY (user_id) ); But before we finish this design, we should consider indexing certain columns. What columns should we index? Well, as a reminder, the columns that are indexed by default are columns with the UNIQUE constraint, and those that are labeled as primary keys. Columns that are not indexed but often should be are those labeled as a foreign key. The column that jumps out the most to me is the creator column of the project table. It's the only foreign key that is not part of some index. Let's fix this by creating our first index. The way we do that is with the CREATE INDEX command. CREATE INDEX projects_creator_ix ON projects (creator) What naming convention are we following for the index? We are naming it by the table name, followed by an underscore, followed by the column, followed by an underscore, followed by an ix (for index). In this situation it does not apply, but if our foreign key column is labeled as UNIQUE, we can add the UNIQUE keyword like this: CREATE UNIQUE INDEX projects_creator_ix ON projects (creator) Now if you want to get rid of an INDEX, you can use this command: DROP INDEX projects_creator_ix Now, if we want to select data from the user table and the project table we can do that much faster. That's because the foreign key and column it references are both indexed and those are the columns we would do the join on. We will discuss how to do joins in a future video. So what are some potential problems with this database design? Overall, it is pretty good. With this design though we need to make sure there is no way for someone to update a user's username. In the next video we are going to discuss why. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me on Patreon! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 6697 Caleb Curry
Oracle Using In , Between and Not تعليم أوراكل
 
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by Mohamed El Desouki - محمد الدسوقى [email protected] Tel :00966 553450836 جامعة سلمان بن عبد العزيز - السعودية - الخرج How to use In , Between and Not. Text Book: Fundamentals of Database Systems, 5th Edition, by Elmasri/Navathe, published by Addison-W oracle create table statement oracle drop table statement oracle constraints database constraints primary key constraint foreign key constraint check constraint null not null constraint unique constraint insert into statement update statement delete statement select statement basic query where clause select where Like '%' Like '_' select where Like select where Between Between , Not Between select where In , Not In
SQL tutorials 20: On Delete Cascade Foreign Key By Manish Sharma (RebellionRider)
 
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Oracle Database 11g Tutorial 20: On delete cascade This tutorial will show you how to define foreign key with on delete cascade clause. Links Blog: http://www.rebellionrider.com/on-delete-cascade.htm SQL Tutorial 19 On delete set Null: http://www.rebellionrider.com/on-delete-cascade.htm SQL Tutorial 19 Foreign Key: http://youtu.be/0nbkBI5r3Gw Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Tool used in this tutorial is SQL Developer. This tutorial series is part of SQL expert exam certification training. if you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Contacts E-Mail [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. http://in.linkedin.com/in/mannbhardwaj/ Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com
Views: 42712 Manish Sharma
How to create Foreign Key Constraint with ON DELETE CASCADE in SQL Server - SQL Server Tutorial 80
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server developer, you need to create two tables with Primary -Foreign Key Relationship. You want to create Foreign Key Constraint with setting if record will be deleted from Referenced Table (Primary Key Column Table), it should be deleted from Parent Table ( Foreign Key Constraint Table) as well. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-create-foreign-key-constraint_29.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 2594 TechBrothersIT
Oracle SQL Tutorial 20 - How to Create Composite Primary Keys
 
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This video is going to be a tutorial on how to create composite and compound keys. The difference between a composite and compound key is that a composite key can consist of any columns while a compound key has to consist of columns that are all keys themselves. We will be working with a compound key because we are going to be using the an intermediary table that has two foreign keys. The combination of both of the keys have to be unique. First, if we have any other CREATE TABLE commands, we are going to comment those out. We will space out the CREATE TABLE to have each column on a line, then we will add constraints as needed. CREATE TABLE project_users( project_id, user_id ) Now, let's add the data types: CREATE TABLE project_users( project_id NUMBER, user_id NUMBER } Now, what about some column attributes? I'm going to make both of the columns NOT NULL because we always want the rows to have a user and a project: CREATE TABLE project_users( project_id NUMBER NOT NULL, user_id NUMBER NOT NULL } Now, let's add the foreign key constraints. Now, what do we name these? We are going to add a primary key that covers both of these columns, so I'm going to be a sinner and not give these constraints names: CREATE TABLE project_users( project_id NUMBER NOT NULL REFERENCES projects (project_id), user_id NUMBER NOT NULL REFFERENCES users (user_id) ) Now, the way we have it now is that if we delete a project in the project table, and there are any rows in the project_users table, it will throw an error and prevent deletion. I would prefer for it to also delete any project members. That would make sense because if you delete a project we want it to delete the associate between that project and certain users. The same goes for if we delete a user, we want their association with a certain project to be deleted. To do this, we need to add the ON DELETE command: CREATE TABLE project_users( project_id NUMBER NOT NULL REFERENCES projects (project_id) ON DELETE CASCADE, user_id NUMBER NOT NULL REFERENCES users (user_id) ON DELETE CASCADE, ) Finally, let's learn how to create a compound or composite key. literally, the only difference is that you put a comma and add the second table inside of the parenthesis. CREATE TABLE project_users( project_id NUMBER NOT NULL REFERENCES projects (project_id) ON DELETE CASCADE, user_id NUMBER NOT NULL REFERENCES users (user_id) ON DELETE CASCADE, CONSTRAINT project_users_pk PRIMARY KEY (project_id, user_id) ) Now, the combination of project_id and user_id cannot be null, is always unique, and has an index. The only thing we should do now is add a few indexes. We aren't done yet...In the next video we are going to figure out what columns would benefit from indexes and we'll add them to it. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HELP ME! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 8333 Caleb Curry
Oracle  Aggregate Functions , Summary Functions
 
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by Mohamed El Desouki - محمد الدسوقى [email protected] Tel :00966 553450836 جامعة سلمان بن عبد العزيز - السعودية - الخرج How to summarize data using Aggregate Functions. كيف تحصل على ملخص للبيانات المخزنة فى عمود معين Text Book: Fundamentals of Database Systems, 5th Edition, by Elmasri/Navathe, published by Addison-W oracle create table statement oracle drop table statement oracle constraints database constraints primary key constraint foreign key constraint check constraint null not null constraint unique constraint insert into statement update statement delete statement select statement basic query where clause select where Like '%' Like '_' select where Like aggregate functions summary functions
CREATE TABLE WITH CONSTRAINTS - ORACLE - SQL
 
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Create table , add constraints : primary key constraint, foreign key constraint, check constraint, unique constraint, specifying the table space for index, modifying table, dropping table Oracle 10g
Views: 9680 R.N.A. Creation
How to Delete Table in sql using oracle 10g or sql
 
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This video gives information about How to Delete Table in sql using oracleXE 10g
Views: 2544 AvilTwo Beginer
How to Generate Script To Enable All Foreign Key Constraints in SQL Server Database - SQL Server P78
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server developer, You need to prepare scripts to enable all the Foreign Key Constraint in a database which are disabled. This could happen, maybe somebody has disabled Foreign Key Constraints for a data load where they don't care about violation of referential integrity and forgot to enable them later. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-generate-script-to-enable-all.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 609 TechBrothersIT
Oracle Primary Key Constraint 2 تعليم اوراكل
 
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by Mohamed El Desouki - محمد الدسوقى [email protected] Tel :00966 553450836 جامعة سلمان بن عبد العزيز - السعودية - الخرج How to Add Primary Key Constraint Using Alter Table Statement.إضافة قيد المفتاح الرئيسى بعد إنشاء الجدول Text Book: Fundamentals of Database Systems, 5th Edition, by Elmasri/Navathe, published by Addison-W oracle create table statement oracle drop table statement oracle constraints database constraints primary key constraint foreign key constraint check constraint null not null constraint unique constraint
Oracle SQL Tutorial For Beginners | Oracle SQL Online Training - Session 2
 
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Course : Oracle SQL Online Training Mode of Training : Online Duration : 40 Hours Timings : Flexible Oracle SQL Online Training Demo Registration Link : http://svsoftsolutions.com/demo.aspx Introduction to SQL What is SQL? What Can SQL do? RDBMS SQL Syntax Database Tables SQL Statements Overview of Most Important SQL Commands SELECT UPDATE DELETE INSERT CREATE TABLE ALTER TABLE DROP TABLE CREATE INDEX DROP INDEX SQL SELECT Statement SELECT syntax Demo Database SELECT Column Example SELECT * Example SQL Distinct SELECT DISTINCT Statement SELECT DISTINCT Syntax SELECT DISTINCT Example SQL WHERE Clause WHERE Clause WHERE Clause Example Operators in the WHERE Clause SQL AND & OR Operators AND Operator Example OR Operator Example Combining AND & OR SQL ORDER BY ORDER BY Syntax ORDER BY Example ORDER BY DESC Example ORDER BY Several Column Examples SQL Insert Into INSERT INTO Syntax INSERT INTO Examples Insert Data into Specified Columns SQL UPDATE UPDATE Syntax UPDATE Example Watch out UPDATE statement. SQL DELETE DELETE Syntax DELETE Examples Delete All the Data SQL Aliases SQL Alias Syntax for Columns Alias Example for Table Columns Alias Example for Tables. SQL Joins Different SQL JOINs INNER JOIN LEFT OUTER JOIN RIGHT OUTER JOIN FULL OUTER JOIN SQL UNION UNION Syntax UNION Example UNION ALL Syntax UNION ALL Example SQL Insert Into Select INSERT INTO SELECT Syntax INSERT INTO SELECT Examples SQL Create Table CREATE TABLE Syntax CREATE TABLE Example SQL Constraints CREATE TABLE + CONSTRAINT Syntax NOT NULL Constraint UNIQUE Constraint UNIQUE Constraint on CREATE TABLE UNIQUE Constraint on ALTER TABLE To DROP a UNIQUE Constraint PRIMARY KEY Constraint PRIMARY KEY Constraint on CREATE TABLE PRIMARY KEY Constraint on ALTER TABLE To DROP a PRIMARY KEY Constraint FOREIGN KEY Constraint FOREIGN KEY Constraint on CREATE TABLE FOREIGN KEY Constraint on ALTER TABLE To DROP a FOREIGN KEY Constraint CHECK Constraint CHECK Constraint on CREATE TABLE CHECK Constraint on ALTER TABLE To DROP a CHECK Constraint DEFAULT Constraint on CREATE TABLE DEFAULT Constraint on ALTER TABLE To DROP a DEFAULT Constraint SQL Create Index CREATE INDEX Syntax CREATE UNIQUE INDEX Syntax CREATE INDEX Example SQL DROP Command The DROP INDEX Statement The DROP TABLE Statement The DROP DATABASE Statement The TRUNCATE TABLE Statement SQL ALTER Command The ALTER TABLE Statement ALTER TABLE Example Change Data Type Example DROP COLUMN Example SQL VIEWS CREATE VIEW Statement CREATE VIEW Syntax CREATE VIEW Examples CREATE OR REPLACE VIEW Syntax Dropping a View SQL NULL Values Working with NULL Values IS NULL IS NOT NULL SQL NULL Functions NVL COALESCE For more details visit our website : www.svsoftsolutions.com Or reach us @ USA : +1-845-915-8712 (Toll Free), India : +91-9642373173
Views: 36 SV Soft Solutions
Oracle SQL Tutorial 17 - Designing Our Foreign Keys
 
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We are going to continue working with the users table that we've started with, but we are going to add a few tables. Imagine a system where you can create projects. And users can be added to these projects. So this could be some kind of productivity app or a project management solution, think of JIRA. We are going to start with three tables. The first table is going to be a users table that contains all of the information about each user's account. We are then going to have a table that is called projects. Each project will have data about the project and a foreign key that is the creator of the project. This is a situation where the database design depends a lot on the business rules and requirements of the application. Is it appropriate to have only one creator, or can it have multiple creators? We are going to design it with only one creator per project to increase simplicity. The third table is going to be used to record what users are part of certain projects. This situation is a many to many relationship because we've decided that one user can be a part of multiple projects and an individual project can have multiple members working on it. Because this is a many to many relationship, it calls for an intermediary table, project_users. First, we will draw out the user table. We will have a user_id, username, first_name, and last_name. Now, this is our parent table, because it has no foreign keys. Now, this is our parent table, because it has no foreign keys. Other tables are going to be referencing this table, so they would be the children. The project table will have a project_id, title, description, and creator. The column that needs to be a foreign key is the creator. Let's move on to the next table and we'll get back to the foreign key of the project table. The other table was project_users. Knowing that this is an intermediary table, immediately we know that the first two columns are going to be foreign keys to the each of the other tables. Now, let's ask the important questions about the foreign keys. Let's first start with the project table's user column. The first thing we need to ask is what column does it need to reference? Remember, the only options are the columns that are UNIQUE. Our candidates are user_id and username. For now, let's go with username as it makes things easier to work with. Once we go into learning about joins, we will talk about joining things by ID. Different people do it different ways, with the majority using only ID columns for primary and foreign keys, but it's important to be familiar with different ways of doing things. The important thing to remember is that keys should never change, so if we should only reference the username if a user's username will never change. Should the foreign key be labeled UNIQUE? If yes, it means that a user can only create one project. I vote no. Should the foreign key be labeled NOT NULL? If not, it means that a project can exist without a creator. I vote no. Moving on to the next table, I think I'll have the columns reference the project's id and user's id, so we can get some experience referencing surrogate keys. We can apply to these foreign keys the same questions we asked about the other foreign key, and I would encourage you to do so and really think about why. But I can tell you that we are not going to want them to be NOT NULL, but not UNIQUE. Now that we have a pretty decent database design, we can proceed with creating our database. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HELP ME! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 7741 Caleb Curry
Primary Key, Foreign Key, NOT NULL, DEFAULT, UNIQUE, and CHECK   ||  Table Constraints in SQL
 
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primary key Learn SQL - SQL CONSTRAINTS CONSTRAINTS - PRIMARY KEY, NOT NULL, etc - SQL Server constraints in dbms | constraints in sql in hindi Oracle SQL Tutorial - How to Add Column Constraints (Attributes) Oracle SQL Constraints Not Null, Primary Key, Unique, Foreign Key and Check Primary Key (PK) Constraint in SQL Server Unique key constraint SQL constraints Working with Primary & Foreign key Constraint in SQL Server | MSSQL Training NOT NULL, DEFAULT, CHECK Constraints (Domain Integrity) in SQL Server Introduction to SQL Constraints
How to disable all Check Constraints in SQL Server Database - SQL Server / TSQL Tutorial Part 87
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server / ETL developer. You need to load bunch of data to tables in SQL Server Database. Check Constraints are created on different tables. There are chances that the data you are going to load will not qualify according to Check Constraint. The business want you to load the data anyways even it does not qualify with Check Constraint. You want to temporary disable all the constraints in SQL Server database and then load the data and then re-enabled the Check Constraints. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/05/how-to-disable-all-check-constraints-in.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 741 TechBrothersIT
How to generate drop Unique Constraint scripts in SQL Server Database - SQL Server Tutorial Part 99
 
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SQL Server / TSQL Tutorial Scenario: You are working as SQL Server developer, you need to generate scripts to drop all Unique Constraints in SQL Server Database. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/05/how-to-generate-drop-unique-constraint.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 423 TechBrothersIT
Truncate All Tables from a SQL Server Database - TSQL Tutorial
 
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Let's think about a database that we use for our ETL process and we call that database staging. We want to truncate all the tables in morning so those can be used for the daily process. Once way is to write our Truncate statement for each of the table but tables can be dropped or new tables can be created as well. We want to write a query that we can be use to Truncate all the tables from a database and we don't have to rewrite our Truncate statements. If the tables do not have Primary Key -Foreign Key relationship, we can use Truncate. But we often have tables which are referenced by other tables. We can not use Truncate statement for those tables. The only way to Truncate those tables is to drop the Foreign Key Constraint before Truncating and then Truncate and Recreate Relationship after that. The below Code can be used to Truncate all the tables from the database. If Tables will have the Pk-Fk relationship, The script will drop the Foreign Key Constraints first and then Truncate those tables and finally recreate the Foreign Key constraints. Before you run below Script, Make sure you are pointing to correct Database and Server! All the best with Truncating all the tables from a SQL Server Database. Link to Blog for Script used in this video http://sqlage.blogspot.com/2015/02/truncate-all-tables-in-database-in-sql.html You can visit our blog http://sqlage.blogspot.com/ Twitter https://twitter.com/AamirSh48904922 Facebook https://www.facebook.com/SqlAge
Views: 31503 TechBrothersIT
SQL Server 34 - How to Create and Drop Indexes
 
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Creating indexes is a very easy task, but before you go creating indexes on everything, you need to know that some columns are indexed by default. Specifically, any column that is labeled as the PRIMARY KEY or UNIQUE are indexed by default. That means that if you have a UNIQUE column, you do not need to worry about adding an INDEX to it. The columns that you will want to pay special attention to are any foreign keys or columns that you are going to use very frequently. We are going to create an index on our SpeciesID column in our Animals table. This is a foreign key that I'm likely going to use very frequently. CREATE INDEX IX_AnimalsSpecies ON Animals (SpeciesID); The syntax is very similar to CREATE TABLE in that you say CREATE INDEX followed by an index name. The IX_ is a prefix that is sometimes conventionally used to name indexes. Next, we have the table name, and then we have something to describe the column. That way if you see IX_AnimalsSpecies, you automatically know it is talking about an Index for the Animals table that is on the column dealing with the species. To get rid of this index, use this: DROP INDEX IX_AnimalsSpecies; Which is also very similar to how we drop a table. Now, you can also create an INDEX on multiple columns if you are going to use them together very often. The way you do that is just add another column after a comma inside of the () in the index columns. For example: CREATE INDEX IX_AnmialsContact ON Animals (Name, ContactEmail); One other thing I wanted to show you is that you can actually create a UNIQUE Index by adding the keyword in: CREATE UNIQUE INDEX IX_Species ON Species (Species); This should only be used if every value for a column is labeled unique…In fact, it forces every row to be unique. Remember though that if a column is labeled UNIQUE, it is indexed by default...So this is not needed in this situation. In the next video we will discuss in more detail whether you want to use the UNIQUE Constraint create a UNIQUE index. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://eepurl.com/-8qtH Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - https://www.dreamhost.com/r.cgi?1487063 (The best web hosting for a cheap price!)
Views: 6183 Caleb Curry
SQL: Default Constraint
 
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In this tutorial, you'll learn how to make use of default constraint PL/SQL (Procedural Language/Structured Query Language) is Oracle Corporation's procedural extension for SQL and the Oracle relational database. PL/SQL is available in Oracle Database (since version 7), TimesTen in-memory database (since version 11.2.1), and IBM DB2 (since version 9.7).[1] Oracle Corporation usually extends PL/SQL functionality with each successive release of the Oracle Database. PL/SQL includes procedural language elements such as conditions and loops. It allows declaration of constants and variables, procedures and functions, types and variables of those types, and triggers. It can handle exceptions (runtime errors). Arrays are supported involving the use of PL/SQL collections. Implementations from version 8 of Oracle Database onwards have included features associated with object-orientation. One can create PL/SQL units such as procedures, functions, packages, types, and triggers, which are stored in the database for reuse by applications that use any of the Oracle Database programmatic interfaces. PL/SQL works analogously to the embedded procedural languages associated with other relational databases. For example, Sybase ASE and Microsoft SQL Server have Transact-SQL, PostgreSQL has PL/pgSQL (which emulates PL/SQL to an extent), and IBM DB2 includes SQL Procedural Language,[2] which conforms to the ISO SQL’s SQL/PSM standard. The designers of PL/SQL modeled its syntax on that of Ada. Both Ada and PL/SQL have Pascal as a common ancestor, and so PL/SQL also resembles Pascal in several aspects. However, the structure of a PL/SQL package does not resemble the basic Object Pascal program structure as implemented by a Borland Delphi or Free Pascal unit. Programmers can define public and private global data-types, constants and static variables in a PL/SQL package.[3] PL/SQL also allows for the definition of classes and instantiating these as objects in PL/SQL code. This resembles usage in object-oriented programming languages like Object Pascal, C++ and Java. PL/SQL refers to a class as an "Abstract Data Type" (ADT) or "User Defined Type" (UDT), and defines it as an Oracle SQL data-type as opposed to a PL/SQL user-defined type, allowing its use in both the Oracle SQL Engine and the Oracle PL/SQL engine. The constructor and methods of an Abstract Data Type are written in PL/SQL. The resulting Abstract Data Type can operate as an object class in PL/SQL. Such objects can also persist as column values in Oracle database tables. PL/SQL is fundamentally distinct from Transact-SQL, despite superficial similarities. Porting code from one to the other usually involves non-trivial work, not only due to the differences in the feature sets of the two languages,[4] but also due to the very significant differences in the way Oracle and SQL Server deal with concurrency and locking. There are software tools available that claim to facilitate porting including Oracle Translation Scratch Editor,[5] CEITON MSSQL/Oracle Compiler [6] and SwisSQL.[7] The StepSqlite product is a PL/SQL compiler for the popular small database SQLite. PL/SQL Program Unit A PL/SQL program unit is one of the following: PL/SQL anonymous block, procedure, function, package specification, package body, trigger, type specification, type body, library. Program units are the PL/SQL source code that is compiled, developed and ultimately executed on the database. The basic unit of a PL/SQL source program is the block, which groups together related declarations and statements. A PL/SQL block is defined by the keywords DECLARE, BEGIN, EXCEPTION, and END. These keywords divide the block into a declarative part, an executable part, and an exception-handling part. The declaration section is optional and may be used to define and initialize constants and variables. If a variable is not initialized then it defaults to NULL value. The optional exception-handling part is used to handle run time errors. Only the executable part is required. A block can have a label. Package Packages are groups of conceptually linked functions, procedures, variables, PL/SQL table and record TYPE statements, constants, cursors etc. The use of packages promotes re-use of code. Packages are composed of the package specification and an optional package body. The specification is the interface to the application; it declares the types, variables, constants, exceptions, cursors, and subprograms available. The body fully defines cursors and subprograms, and so implements the specification. Two advantages of packages are: Modular approach, encapsulation/hiding of business logic, security, performance improvement, re-usability. They support object-oriented programming features like function overloading and encapsulation. Using package variables one can declare session level (scoped) variables, since variables declared in the package specification have a session scope.
Views: 4960 radhikaravikumar
17. RENAME Table and DROP Table in Oracle
 
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In this video I will show you how to change the name of existing table and also how to drop the table. Dropping table can delete your all records exist in that database table. For Support =========== Email: [email protected] Contact Form: http://www.learninhindi.com/home/contact Our Social Media ================ Facebook: https://www.facebook.com/LearnInHindi Twitter: https://twitter.com/LearnInHindi For Training & Videos ===================== For more videos and articles visit: http://www.learninhindi.com Free Java Programming In Hindi Course ===================================== https://www.youtube.com/playlist?list=PLOZ3jentlCDAwwhMyoLISrxkXTADGp7PH Free Oracle PL/SQL Programming In Hindi Course ============================================== https://www.youtube.com/playlist?list=PLB5DA82419C2D99B6 Free C Programming In Hindi Course ================================== https://www.youtube.com/playlist?list=PLOZ3jentlCDAxKpBLMWogxSdy6BZcsAJq Trips & Tricks Channel ====================== https://www.youtube.com/channel/UCGmLfkuCo-3lHHJXRJ9HUMw Programming in Hindi Channel ============================ https://www.youtube.com/channel/UCudElIDgwNrybeAvXIy1HZQ
Views: 29715 ITORIAN
how to add and drop primary key in sql server 2008 and 2012
 
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How to add primary key in sql by query. To allow naming of a PRIMARY KEY constraint and describe how to drop primary keys .
Views: 8612 Programming School
SelectTec | Aula Nº 30 | Alter table add Foreign Key - Oracle SQL Developer
 
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syntax: ALTER TABLE table_name ADD CONSTRAINT constraint_name FOREIGN KEY (column1, column2, ... column_n) REFERENCES parent_table (column1, column2, ... column_n);
Views: 1703 SelectTec
PostgreSQL - Drop all tables of a Database
 
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drop schema public cascade; create schema public;
Views: 2155 Bhaskar Reddy Pulsani