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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://bit.ly/JoinCCNewsletter 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 - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 17817 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://bit.ly/JoinCCNewsletter 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 - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 17998 Caleb Curry
Oracle - SQL - Constraints
 
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Oracle - SQL - Constraints Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
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: 99087 Manish Sharma
Oracle - SQL - Check Constraint
 
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Oracle - SQL - Check Constraint Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
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://bit.ly/JoinCCNewsletter 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 - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 12918 Caleb Curry
Oracle - SQL - Foreign Key Constraint
 
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Oracle - SQL - Foreign Key Constraint Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
SQL: Check Constraint
 
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In this tutorial, you'll learn how to make use of check 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: 11403 radhikaravikumar
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: 97074 Manish Sharma
Oracle - SQL - Managing Constraints
 
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Oracle - SQL - Managing Constraints Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
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://bit.ly/JoinCCNewsletter 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 - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 13299 Caleb Curry
Oracle Tutorial || Oracle| Sql Constraints Part - 1 by basha
 
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Oracle Constraints
 
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Oracle SQL Tutorials For Full Course Experience Please Go To http://mentorsnet.org/course_preview?course_id=4 Full Course Experience Includes 1. Access to course videos and exercises 2. View & manage your progress/pace 3. In-class projects and code reviews 4. Personal guidance from your Mentors
Views: 20129 Oresoft LWC
OracleSQL#61 Check constraint in Oracle SQL Database| How to Add Check Constraints
 
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How to use Check Constraint in Oracle or what is Constraints and Types of Constraints in an Oracle SQL Database | integrity Constraints in SQL. Check Constraint is nothing but it allows you to specify a condition on each row in the table Explaining constraints and types of constraints in Oracle or Constraints in Oracle SQL database or Constraints is nothing but a set of rules which is applied to the columns of any table in the database ------------------------------------ Assignment link : ----------------------------------- https://drive.google.com/open?id=1uQBEYQ0e9Wszk5BIigz4CJ7ow4aPKL4B In this series we cover the following topics: SQL basics, create table oracle, SQL functions, SQL queries, SQL server, SQL developer installation, Oracle database installation, SQL Statement, OCA, Data Types, Types of data types, SQL Logical Operator, SQL Function,Join- Inner Join, Outer join, right outer join, left outer join, full outer join, self-join, cross join, View, SubQuery, Set Operator. follow me on: Facebook Page: https://www.facebook.com/LrnWthr-319371861902642/?ref=bookmarks Contacts Email: [email protected] Instagram: https://www.instagram.com/equalconnect/ Twitter: https://twitter.com/LrnWthR
Views: 26 EqualConnect Coach
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
Constraint In Oracle PL SQL
 
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Constraint In Oracle PL SQL oracle tutorial for beginners A) UNIQUE CONSTRAINT : A unique constraint is uniquely defines a record. Its value is not repeated. It can be null. B)NOT NULL CONSTRAINT: Not null constraint restrict from inserting null values. If we want some columns does not take null values then we can use this constraint. C)CHECK CONSTRAINT: A check constraint allows you to specify a condition on particular column in a table. we can add our custom logical conditions. CREATE TABLE TEST2 ( ID VARCHAR2(10) UNIQUE, NAME VARCHAR2(50), DEPT VARCHAR2(10) NOT NULL, AGE NUMBER(10), CHECK (AGE BETWEEN 18 and 60) ); #techquerypond https://techquerypond.wordpress.com https://techquerypond.com https://twitter.com/techquerypond
Views: 173 Tech Query Pond
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://bit.ly/JoinCCNewsletter 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 - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 18903 Caleb Curry
Oracle - SQL - Primary Key Constraint
 
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Oracle - SQL - Primary Key Constraint Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
Oracle - SQL - Unique Constraint
 
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Oracle - SQL - Unique Constraint Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
Oracle SQL Tutorial 14 - Column-Level and Table-Level Constraints
 
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In the previous video we talked about adding constraints at the column-level. We made it nice and simple by only requiring a few keywords, but the problem we were having is that we could not assign a name to the constraint, which many people like to do so we can reference easily if we need to at a later time. To do this, it requires a little bit more typing, but it will give us extra flexibility and many consider it to be the higher quality approach to adding constraints. Let's go though a simple example. Let's say we have a users table with a user_id column that we want to make a primary key. We will create the table like this: CREATE TABLE( user_ id NUMBER PRIMARY KEY ) Instead of adding the PRIMARY KEY keywords after the data type, we add: CONSTRAINT user_pk PRIMARY KEY Now, we have assigned the name user_pk to this constraint. You can do the same with other constraints, such as UNIQUE. The syntax would be CONSTRAINT username_un UNIQUE. The other way to create constraints requires to put all of our constraints at the bottom of our table creation rather than inline with the column. This type of constraint is known as a table-level constraints. To make a column a primary key using table-level constraints, we add it to the CREATE TABLE command as if it is another row and use the CONSTRAINT keyword to tell Oracle that what is coming is a constraint, not a column in our table. CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR), CONSTRAINT username_un UNIQUE (username), CONSTRAINT users_pk PRIMARY KEY (user_id) ) The primary differences here is that you have to put the column you are talking about in parenthesis after the PRIMARY KEY keyword. That's because it's at the end of the table and you need a way to tell it what column you are talking about. The option of putting it at the end of the table has the added benefit in this situation because if we needed to have a primary key that is the combination of multiple columns, we can do that by just adding the other column in the PRIMARY KEY parenthesis right after a comma. In summary, there are three ways to make constraints. The first is at the column level, unnamed. The second is at the column level, named. The third is at the table level, also named. In the next video we are going to create a named constraint in Oracle SQL Developer, so stay tuned and be sure to subscribe! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter 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 - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 13241 Caleb Curry
Oracle Sql 4: alter table constraints
 
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add y drop check, unique, primary key
Views: 1524 tomas bonilla
45. Primary Key and Foreign Key Constraints in PL/SQL Oracle
 
12:36
In this video you will learn about Primary Key and Foreign Key Constraints in PL/SQL Oracle. 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: 9215 ITORIAN
CREATE TABLE WITH CONSTRAINTS - ORACLE - SQL
 
20:35
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: 9812 R.N.A. Creation
Creating data model with Oracle SQL Developer  - Part 1
 
20:22
This video tutorial is about creating a data model on existing schema using Oracle SQL Developer. This tutorial also includes adding referential constraints with data model and generating DDL from the data model.
Views: 4671 Subhroneel Ganguly
Oracle SQL Constraints
 
29:35
In the previous video, we talked about creating users and granting privileges to users in Oracle 10G. In this video, we are going to talk about constraints and see a simple query related to constraints. Topics covered in this video are : -Constraints -Reason for learning Constraints in DBMS -Defining Constraints on Table Level or Column Level -Guidelines for defining the name of the constraint -Types of Constraints -Adding Constraints to existing Table -Enabling or Disabling constraints -Dropping Constraints
Views: 42 Ajay Technical
Oracle database Training : How to add constraints in Table
 
10:29
Oracle SQL Constraints Oracle Training in Bangladesh Oracle Developer and Database Training in Bangladesh Oracle Training at Dev Net IT Oracle forms Training for details http://www.devnet-it.com
Views: 430 devnetbd devnetit
Adding a check constraint - Part 6
 
11:39
In this video we will learn 1. How to add a check constraint in SQL Server 2. The purpose or use of check constraint Text version of the video http://csharp-video-tutorials.blogspot.co.uk/2012/08/check-constraint-in-sql-server-part-6.html Slides http://csharp-video-tutorials.blogspot.com/2013/08/part-6-check-constraint.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 376987 kudvenkat
ADD CONSTRAINT FOREIGN KEY, INSERT VALUES in Oracle SQL
 
06:50
Oracle SQL tutorials, How to ADD CONSTRAINT FOREIGN KEY, INSERT INTO statement
Oracle Tutorial || Oracle| Sql Constraints Part - 2 by basha
 
36:16
DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
Oracle - SQL - Not Null Constraint
 
05:14
Oracle - SQL - Not Null Constraint Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
UNIQUE KEY CONSTRAINT IN ORACLE SQL WITH EXAMPLE
 
14:37
This is a free video tutorial by Kishan mashru on unique constraint in Oracle SQL, the video firstly explains what unique constraint is and how it can be used along with its various limitations, then the video gives perfect examples to understand how to create a unique key at the column level or inline, or at the table level i.e out of line. The video gives a demonstration on ALTER TABLE ADD CONSTRAINT and ALTER TABLE DROP CONSTRAINT statements also.
Views: 917 Kishan Mashru
56. ALTER TABLE to ADD and DROP integrity constraints in PL/SQL Oracle
 
10:39
In this video you will learn about ALTER TABLE to ADD and DROP integrity constraints in PL/SQL Oracle. 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: 3174 ITORIAN
Oracle SQL Tuning with Foreign Key Constraints
 
03:02
Learn how to tune SQL with Constraints! In this lesson (2 of 5), OCM John Watson demonstrates how to improve query performance by adding foreign key constraints. See all lessons, free at http://www.skillbuilders.com/oracle-database-sql-tuning-with-constraints.
Views: 430 SkillBuilders
SQL: Default Constraint
 
04:17
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: 5414 radhikaravikumar
SQL: Foreign Key Creation
 
05:55
In this tutorial, you'll learn how to create a foreign key column ....
Views: 38168 radhikaravikumar
How to Resolve Oracle SQL Parent Key Not Found (ORA-02291)
 
05:49
In this video, we’ll explain what the ORA-02291 “parent key not found” error is, see an example, and look at how to resolve it. This error usually happens when we try to insert data into a table. It looks like this: Error is: ORA-02291: integrity constraint (constraint_name) violated - parent key not found So what does this error mean? It means we’re trying to insert data into a child table, and there is no related record in the parent table. If a foreign key has been set up to enforce this relationship, there needs to be a parent to insert a child that refers to it. Watch the video to see an example of this error as well as how to resolve it. For more information on Oracle SQL, refer to the Database Star website here: https://www.databasestar.com/
Views: 1258 Database Star
PRIMARY KEY CONSTRAINT IN ORACLE SQL WITH EXAMPLE
 
12:43
This is a free video tutorial by Kishan mashru on primary key constraint in oracle SQL, the video firstly explains what primary key constraint is and how it can be used along with its various limitations, then the video gives perfect examples to understand how to create a primary key at the column level i.e inline declaration, or at the table level i.e out of line declaration. The video gives the demonstration on ALTER TABLE ADD CONSTRAINT and ALTER TABLE DROP CONSTRAINT statements also.
Views: 558 Kishan Mashru
Oracle Database11g tutorials 14 : How to CREATE TABLE using sql developer and command prompt
 
08:36
Oracle Database11g tutorials 14 How to Create table using command prompt and Create table using sql developer Blog Link http://bit.ly/1TkY4Oe Time Line 0:25 Introduction of Tables in Database 1:03 What is Create Table (Introduction of create table) 1:30 Syntax of Create Table 2:08 How to create table using Command Prompt 4:55 How to create table using SQL Developer Links for Oracle Database tutorials 4: database connectivity using SQL developer and command prompt http://youtu.be/wSqoXRlXDUU You can have indepth knowledge about SQL create table here http://www.rebellionrider.com/sql-create-table.html Tool used in this tutorial is command prompt. 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 Today in this oracle database tutorial we will see How to CREATE A TABLE. if we have to define a table in layman language then we can say that Tables are just a collection of Rows and Columns but In RDBMS tables are database objects which help in organizing data into ROWS and COLUMNS. We can also say that SQL tables are kind of data structure which are used by database for efficient storage of data. To create a table in our database we use SQL CREATE TABLE command. SQL CREATE TABLE is a type of DATA DEFINITION LANGUAGE also known as DDL. To Create a table in your schema you will require CREATE TABLE system privilege. In our future videos we will see what are system and object privileges and how to grant them to a user. Today for this video we will be using Sample schema HR which already has all the necessary privileges. Ohk Let's see the syntax. CREATE TABLE table name ( column name1 Data-Type(size), column name2 Data-Type(size), ..... ); CREATE TABLE is an oracle reserved word or say an Oracle key word whereas There are 3 different ways of creating a table in Oracle database. Creating a table using Command Line Interface (CLI) in Oracle database For demonstrating how to create table in oracle database using CLI, I'll be using Command prompt. Thats how we create table using command prompt. you can check your table structure by DESCRIBE command for that just write DESC and your table name. Like this Another way of creating a table is by using Graphic user interface (GUI) in Oracle database To demonstrate how to create table using GUI we will use SQL developer. Lets open our SQL developer I am connected to HR schema if you do not know how to create a connection to database using SQL developer please watch my oracle database tutorial 4 that explains database connectivity using SQL developer and command prompt. Link for this video is in the description below. So lets create a table. Creating a table using SQL developer is very easy we do not have to fire any query here. Let's start First of all right click on your connection in which you want to create a table and choose schema browser. This will open a separate schema browser pane or you can expend your connection by clicking this + sign and then right click on table and choose New Table. However I prefer working with schema browser so let's skip to schema browser pane here from the first drop-down list you can choose connection name and in the second drop down list you can choose what database objects you want to work with we want to create a table thus I'll choose table and then click this arrow here and choose option for new table Ok we have created a table wizard first of all give a unique name to your table and add some column as well. For this, click the green plus button. Now we already have a column so give it some name. Also choose a datatype from the list and specify any size you can check this not null column if in case you want to make this a mandatory column you can also specify default value and constraint If you want to make this column a primary key you can click here In my future video i'll show you what are these constraints and different ways of applying them on a column in a table. for this video we will concentrate on create table only so when you are done with all your columns click ok Thats your table You can double click on your table here and can see its structure. Thats it
Views: 169196 Manish Sharma
61. ALTER TABLE for Adding Constraint in Column SQL (Hindi)
 
03:40
Please Subscribe Channel Like, Share and Comment Visit : www.geekyshows.com
Views: 7506 Geeky Shows
SQL Create Database, Create Table, Constraints in Table - Theory
 
06:48
SQL Create Database, Create Table, Constraints in Table - Theory For Students of B.Tech, B.E, MCA, BCA, B.Sc., M.Sc., Courses - As Per IP University Syllabus and Other Engineering Courses
Working with Primary & Foreign key Constraint in SQL Server | SQL Server Tutorial
 
24:13
** For Online Training Registration: https://goo.gl/r6kJbB ? Call: +91-8179191999 ? Visit Our Website for Classroom Training: https://nareshit.in/sql-server-training/ ? For Online Training: https://nareshit.com/course/sql-server-online-training/ #sqlserver #server #programming #course #Tutorials #Training #Videos -------------------------- ? About NareshIT: "Naresh IT is having 14+ years of experience in software training industry and the best Software Training Institute for online training, classroom training, weekend training, corporate training of Hadoop, Salesforce, AWS, DevOps, Spark, Data Science, Python, Tableau, RPA ,Java, C#.NET, ASP.NET, Oracle, Testing Tools, Silver light, Linq, SQL Server, Selenium, Android, iPhone, C Language, C++, PHP and Digital Marketing in USA,Hyderabad, Chennai and Vijayawada,Bangalore India which provides online training across all the locations -------------------------- ? Our Online Training Features: 1.Training with Real-Time Experts 2.Industry Specific Scenario’s 3.Flexible Timings 4.Soft Copy of Material 5. Share Videos of each and every session. -------------------------- Please write back to us at [email protected]/[email protected] or Call us at USA: +1404-232-9879 or India: +918179191999 ** Check The Below Links** ? For Course Reg: https://goo.gl/r6kJbB ? Subscribe to Our Channel: https://goo.gl/q9ozyG ? Circle us on G+: https://plus.google.com/NareshIT ? Like us on Facebook: https://www.facebook.com/NareshIT ? Follow us on Twitter: https://twitter.com/nareshitech ? Follow us on Linkedin: https://in.linkedin.com/company/naresh-i-technologies ? Follow us on Instagram: https://www.instagram.com/nareshitech/
Views: 51808 Naresh i Technologies
Oracle Database SQL Tutorials 29 :: How to Alter Statement  using SQL ,Add Constraint,column
 
06:38
www.facebook.com/oracle.shohag Email : [email protected] Website : www.oraclebangla.com Topics : How to Alter Statement Object Structure using SQL ,Add Constraint,column add Oracle Database SQL Tutorials | how to Alter a table structure using SQL | Oracle Bangla 2017 How to alter a Table Structure using SQL | Alter statement | SQL tutorials | Oracle Bangla 2017 | HD Oracle SQL Tutorials. how to alter a table using sql
Views: 1078 Oracle Bangla
SQL Foreign Key Constraints
 
07:25
Jamie King of Neumont University showing what are and how to add foreign key constraints.
Views: 52206 Jamie King
Oracle SQL Tutorial 16 - Parent Child Relationships
 
06:09
So far in this series we have discussed database design, creating tables, and constraints. We've brought up the concept of foreign keys, but we have not explained how to create them. That is the goal of this video and the upcoming videos. We want to study those foreign keys! Let's make them not so foreign. Let's learn the proper way to define a foreign key. As a reminder, a foreign key is a column that references a column of another table. The column it references must either be a primary key, or have the UNIQUE constraint. This means that every value inside of the column that is labeled as a foreign key, there must be that value in some row of the referenced column. As an example, imagine that we have the users table, and we have a table service_requests. We could have a column in the service_request that references a column in the users table. Usually this would be the primary key that is referenced, but there is nothing stopping you from referencing a unique column. Just for fun, let's go through an example using the username column. If we have a service_requests table, every single row within the table is going to be what some would consider an instance of a service_request. This means that the table columns are like the blueprint for what a service request looks like and then each row is an individual service request. If we have one of the columns labeled as a foreign key to the username of the users table, what does that mean practically? It means that for a single row, the value for that column must be a value that exists in the users table. We could have a service_request submitted by a user with the username of Yoloswagman. This means that there must be a row inside of the users table that has the value Yoloswagman for the username column. This brings up the concept of parent and child relationships. Yoloswagman in this situation is the parent, and his service request is the child. When we draw it out, it makes sense why a primary key must be UNIQUE. If we had two Yoloswagmans, the child would not know which column is the parent. The same applies if we were using IDs and we had So remember, always reference a primary key or a column with the UNIQUE constraint. Now, I have a question for you. Do foreign keys automatically have the UNIQUE constraint, just like primary keys? The answer is no. A parent row can have many child rows. It makes sense because the user could submit multiple service requests. Can we force the column to be unique? Absolutely. If that was the case, the user could only make one service request. Another question. Do foreign keys automatically have the NOT NULL constraint, just like primary keys? The answer is no. Essentially what this means is that a child could be created with no parent. Can we force the column to be NOT NULL? Absolutely. It is ok in some situations to allow the row to be null, but in this situation it makes no sense. It would be wise for us to add that constraint ourselves. So now that you understand some more differences between primary and foreign keys and parent child relationships, take all of these questions into consideration when you are creating foreign keys. In the next video, we are going to start a small project that is going to require multiple tables. We'll take a video to design our structure and then we'll get to creating those foreign keys in Oracle SQL Developer. Stick around and if you like these videos please be a serious supporter and subscribe to my channel. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HELP ME! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter 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 - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 10871 Caleb Curry
Oracle SQL Tutorial 21 - How to Create / Drop Indexes
 
03:58
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://bit.ly/JoinCCNewsletter 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 - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 7613 Caleb Curry
Set business rules with check constraints in oracle.
 
19:01
Check constraint is used to validate data according to business logic, whether it be limiting the value range or allowing some specific string format or data format. This oracle tutorial is about how to add, remove, enable or disable check constraints in oracle 12c. Here are the list of ddl commands for check constraint: ALTER TABLE table_name ADD CONSTRAINT constraint_name CHECK column_name condition [DISABLE]; ALTER TABLE table_name DROP CONSTRAINT constraint_name; ALTER TABLE table_name ENABLE CONSTRAINT constraint_name; ALTER TABLE table_name DISABLE CONSTRAINT constraint_name;
Views: 475 Subhroneel Ganguly
Oracle SQL Tuning with Unique Constraints
 
02:28
Learn how to tune SQL with Constraints! In this lesson (4 of 5), OCM John Watson from SkillBuilders demonstrates how to improve query performance by adding not null constraints. See all lessons, free at http://www.skillbuilders.com/oracle-database-sql-tuning-with-constraints.
Views: 285 SkillBuilders
constraint in dbms/sql - (null / notnull, check, default , unique, primary key constraints)
 
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constraint in sql with examples, null / notnull, check, default , unique, primary key constraints dbms constraints, DBMS videos. .................................................... GATE lectures on SIGNAL AND SYSTEM - by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI1qBFREKxhFbBR8veKrYj60 GATE lectures on ANALOG ELECTRONICS - by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI0SzA4wJDv7EqfgCHaRtunH&disable_polymer=true DIGITAL COMMUNICATION by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI0-af8Lr1S5Bwbv4_-kbi-4 DIGITAL LOGIC DESIGN - by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI0V04wTbaqUWvcvAE_B98Qj DSP by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI1VEDhEOVNHrTs_pzt684ou signal and system by SHRENIK JAIN https://www.youtube.com/playlist?list=PLfP-D1tg0DI2Fpj_oV4VvLax4JJVL_kW2 DBMS by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI0D1MSTRXFr1X6bb_ZI0E7W ANALOG ELECTRONICS by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI3HaJdHpBu7XX-m9c6mANZk ANALOG ELECTRONICS-2 by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI3tNQmWNnSrGydZ1tQUSMXy OPERATING SYSTEM -by SHRENIK JAIN https://www.youtube.com/playlist?list=PLfP-D1tg0DI1U3Xe4ynk6ocVQl2qKoDoB CONTROL SYSTEM - by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI1Cwku-ZLD-ofrsLHd5dHQy Engineering Maths https://www.youtube.com/playlist?list=PLfP-D1tg0DI0Kavkv81ZvQI8g7VSiVIm_ VLSI - by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI2Sn1DVzGdIeGyuIUjhJ9zp Limits and Continuity - by Siddhant Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI3Ln9qhdNlIbRR1gAqrGXH0 INTEGRATED CIRCUIT (IC) by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI1yEx1fdhqA8jR5WtCJvQN5 IMAGE PROCESSING - by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI2F_PAG8Z6WxZgqBK0jG_-D PROBABILITY by Shrenik Jain https://www.youtube.com/playlist?list=PLfP-D1tg0DI2KD99RmEobWaLiG4bZPNPN .................................................... ANY DOUBT ? ASK ON FB page . facebook link : https://www.facebook.com/studysimplified/ quora link : https://www.quora.com/profile/Shrenik-Jain-51
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