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What is the Difference between Primary Key and Unique Key - Database Tutorial 14
 
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Database Tutorial. This video is about Database Fundamentals. I hope this series of videos can help those who want to be Database Professionals. I will cover various database technologies including Oracle Database, Microsoft SQL Server database and Sybase. Video: What is the Difference between Primary Key and Unique Key (Video 14 in the Database Tutorial Series) (Common for Oracle/Microsft SQL Server/Sybase /MySQL)
Views: 34278 Sam Dhanasekaran
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://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: 8380 Caleb Curry
Differences between primary key and unique key - SQL Server Interview Questions
 
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Hi Friends, In this in this session we are going to learn the differences between primary key and unique key This is one of the most frequently asked sql server interview questions. Before we discuss the difference between primary key and unique key, let's see what a primary key is and what a unique key is. Primary Key: Primary key is a key which uniquely identifies each row/record in the table. This implies if you have a primary key on a table, you can identify each and every row in that table uniquely using primary key. Unique Key: Unique key constraint enforces the uniqueness on the columns in which it is defined. That is Unique key will make sure only unique values are allowed in the columns in which it is defined. Similarities: Both Primary key and unique Key enforces uniqueness on the columns on which they are defined. • Primary key and unique Key columns allow only unique values. • Primary key and unique Key columns will avoid duplicates • Both Primary key and unique Key columns uniquely identifies each row/record in the table Differences: PRIMARY KEY UNIQUE KEY Primary Key Does not allow duplicates Unique key allows only one NULL A table can have only 1 Primary Key A table can have multiple Unique Keys By default Primary Key creates a Unique Clustered Index on the table By default Unique Key creates a Unique Non-Clustered Index on the table. I hope this session is clear and i hope this knowldge should help you in interviews. Please share your valuable comments & sugesstions. Also, subscriber to my channel for more sql server interview questions and answers. Bye bye & Have a good day.
Views: 39017 TheSSScreations
Database Design 21 - Primary Key Index
 
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Donate!: http://bit.ly/DonateCTVM2. Primary key will automatically create an index used for database optimization! More content: http://CalebCurry.com Courses for Download: http://www.udemy.com/u/calebcurry/ Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://Twitter.com/calebCurry Subscribe (it's free!): http://bit.ly/PqPyvH Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 17085 Caleb Curry
DIFFERENCE BETWEEN PRIMARY KEY AND UNIQUE KEY CONSTRAINT IN ORACLE SQL
 
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This video tutorial explains about the difference between primary key and unique key in oracle sql which is also a to be asked interview quiestion. After watching this video you will be able to explain the difference between both the constraints.
Views: 1998 Kishan Mashru
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://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: 10491 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 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://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: 43637 Caleb Curry
SQL tutorial 62: Indexes In Oracle Database By Manish Sharma RebellionRider
 
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Watch and learn concepts of SQL Index In Oracle Database. In this tutorial you will learn about B-Tree Index and Function based Index. ------------------------------------------------------------------------ ►►►LINKS◄◄◄ Blog : Previous Tutorial ► ------------------------------------------------------------------------- ►►►Help Me In Getting A Job◄◄◄ ►Help Me In Getting A Good Job By Connecting With Me on My LinkedIn and Endorsing My Skills. All My Contact Info is Down Below. You Can Also Refer Me To Your Company Thanks ------------------------------------------------------------------------- Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=kb4rc1 -------------------------------------------------------------------------- ►Make sure you SUBSCRIBE and be the 1st one to see my videos! -------------------------------------------------------------------------- Amazon Wishlist: http://bit.ly/wishlist-amazon ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ►►►Find me on Social Media◄◄◄ Follow What I am up to as it happens on https://twitter.com/rebellionrider https://www.facebook.com/imthebhardwaj http://instagram.com/rebellionrider https://plus.google.com/+Rebellionrider http://in.linkedin.com/in/mannbhardwaj/ http://rebellionrider.tumblr.com/ http://www.pinterest.com/rebellionrider/ You can also Email me at for E-mail address please check About section Please please LIKE and SHARE my videos it makes me happy. Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com ♥ I LOVE ALL MY VIEWERS AND SUBSCRIBERS
Views: 40787 Manish Sharma
Unique Key Concept
 
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http://zerotoprotraining.com Unique Key Concept Category: Oracle SQL Tags: Unique Key
Views: 2744 HandsonERP
Oracle SQL Tutorial 8 - Indexes - Database Design Primer 5
 
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The concept of an index is extremely important when managing a database. An index has the power of making your database very quick or it has the power to bog down your update, delete, and insert statements. The trick is to find a good balance. You will want to index any columns that are used continually in a select or a join. By default, all primary keys are indexed as well as any columns with the UNIQUE column attribute. I suggest you consider adding an index to your foreign keys as these will often be used in joins as well. You can actually create an index on a group of columns. This will allow you to search for data and return multiple columns. This is known as a composite index. There are many other things to database design...much more than we have covered. I have decided I will cover these as we go so that we can start applying what we learn practically. 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: 16933 Caleb Curry
45. Primary Key and Foreign Key Constraints in PL/SQL Oracle
 
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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: 10195 ITORIAN
UNIQUE KEY CONSTRAINT IN ORACLE SQL WITH EXAMPLE
 
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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: 993 Kishan Mashru
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.
What are Clustered Indexes vs. Non-Clustered in SQL Server 2008 R2 Software Tutorial
 
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What are clustered indexes? How are they created? What is the connection between the primary key and the clustered index? How do I optimize the performance of SQL Server 2008 tables by using indexes? Try our free sales and customer reporting web service at http://www.reportingsales.com
Views: 58247 Edward Kench
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://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: 8089 Caleb Curry
Difference between Primary key, Unique and Index in MySql
 
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Digging deep into the attributes of mysql column fields, difference between index, unique and primary key. For more videos visit http://www.tutoslive.com/classDetails/73/Create-Retrieve-Update-and-Delete-Data-in-MySql To attend a live class visit http://www.tutoslive.com For interesting questions and solutions join our facebook group https://www.facebook.com/groups/tutoslive/ For exciting offers follow us on twitter at @tutoslivenow
Views: 2711 Tutoslive
Clustered vs. Nonclustered Index Structures in SQL Server
 
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Clustered and nonclustered indexes share many of the same internal structures, but they're fundamentally different in nature. Watch Microsoft Certified IT Professional Jon Seigel explain the similarities and differences of clustered and nonclustered indexes, using a real-world example to show how these structures work to improve the performance of SQL queries. Blog post on primary key vs. the clustered index: http://voluntarydba.com/post/2012/10/02/The-Primary-Key-vs-The-Clustered-Index.aspx CREATE INDEX statement reference: http://technet.microsoft.com/en-us/library/ms188783.aspx ALTER INDEX statement reference: http://technet.microsoft.com/en-us/library/ms188388.aspx Index navigation internals by example: http://sqlblog.com/blogs/paul_white/archive/2011/08/09/sql-server-seeks-and-binary-search.aspx Sample index data is from the AdventureWorksLT2008R2 sample database: http://awlt2008dbscript.codeplex.com/releases/view/46169 Visit my channel for more database administration videos: https://www.youtube.com/voluntarydba Subscribe to get notified about my latest videos: https://www.youtube.com/voluntarydba?sub_confirmation=1 Read additional content on my blog: http://voluntarydba.com Follow on Twitter: https://twitter.com/voluntarydba Like on Facebook: https://facebook.com/voluntarydba
Views: 288040 Voluntary DBA
Foreign Key | Database Management System
 
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To ask your doubts on this topic and much more, click on this Direct Link: http://www.techtud.com/video-lecture/lecture-foreign-key IMPORTANT LINKS: 1) Official Website: http://www.techtud.com/ 2) Virtual GATE: http://virtualgate.in/login/index.php Both of the above mentioned platforms are COMPLETELY FREE, so feel free to Explore, Learn, Practice & Share! Our Social Media Links: Facebook Page: https://www.facebook.com/techtuduniversity Facebook Group: https://www.facebook.com/groups/virtualgate Google+ Page: https://plus.google.com/+techtud/posts Last but not the least, SUBSCRIBE our YouTube channel to stay updated about the regularly uploaded new videos.
Views: 257568 Techtud
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.
PRIMARY KEY and UNIQUE KEY Constraints in Oracle Database
 
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unique constraint oracle oracle check constraint alter table add constraint primary key oracle oracle unique constraint multiple columns oracle unique constraint vs unique index
Views: 6 Adam Tech
Oracle Unique Constraint 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 Unique Constraint to Table. Unique كيف تستخدم قيد الــ 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
SQL Server training and interview question:-What is index and how does it make your search faster ?.
 
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For more such videos visit http://www.questpond.com See our other Step by Step video series below :- Learn Angular tutorial for beginners https://tinyurl.com/ycd9j895 Learn MVC Core step by step :- http://tinyurl.com/y9jt3wkv Learn MSBI Step by Step in 32 hours:- https://goo.gl/TTpFZN Learn Xamarin Mobile Programming Step by Step :- https://goo.gl/WDVFuy Learn Design Pattern Step by Step in 8 hours:- https://goo.gl/eJdn0m Learn C# Step by Step in 100 hours :- https://goo.gl/FNlqn3 Learn Data structures & algorithm in 8 hours :-https://tinyurl.com/ybx29c5s Learn SQL Server Step by Step in 16 hours:- http://tinyurl.com/ja4zmwu Learn Javascript in 2 hours :- http://tinyurl.com/zkljbdl Learn SharePoint Step by Step in 8 hours:- https://goo.gl/XQKHeP Learn TypeScript in 45 Minutes :- https://goo.gl/oRkawI Learn webpack in 50 minutes:- https://goo.gl/ab7VJi Learn Visual Studio code in 10 steps for beginners:- https://tinyurl.com/lwgv8r8 Learn Tableau step by step :- https://tinyurl.com/kh6ojyo Preparing for C# / .NET interviews start here http://www.youtube.com/watch?v=gaDn-sVLj8Q In this SQL Server training video we will understand what are indexes and how they make your search faster. We also run through the fundamentals of B-tree or balanced tree structure. Its also one of those favourite SQL Server interview questions which is asked in SQL Server interviews. We are also distributing a 100 page Ebook "Sql Server Interview Question and Answers". If you want this ebook please share this video in your facebook/twitter/linkedin account and email us on [email protected] with the shared link and we will email you the PDF.
Views: 227738 Questpond
Creating a Unique Constraint in Microsoft SQL Server Management Studio
 
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Here is a quick tutorial on Creating a Unique Constraint in Microsoft SQL Server Management Studio using the Microsoft AdventureWorks database.
Views: 11733 Roland Martin
Primary key and Foreign Key in DBMS
 
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Primary key vs Foreign key in DBMS. Key concepts in DBMS. (Candidate key, Primary Key, Foreign Key, Alternate Key, Super Key)
Views: 165258 Edu Therapy
SQL Constraints - NOT NULL , UNIQUE , PRIMARY KEY , FOREIGN KEY , CHECK , INDEX , default
 
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SQL is a standard Structured query language for storing, manipulating and retrieving data in databases. NOT NULL , UNIQUE , PRIMARY KEY , FOREIGN KEY , CHECK , INDEX , default 1) NOT NULL - Ensures that a column cannot have a NULL value 2) UNIQUE - Ensures that all values in a column are different 3) PRIMARY KEY - A combination of a NOT NULL and UNIQUE. Uniquely identifies each row in a table 4) FOREIGN KEY - Uniquely identifies a row/record in another table. The table containing the foreign key is called the child table, and the table containing the candidate key is called the referenced or parent table. prevents invalid data and destroy links between tables. 5) CHECK - Ensures that all values in a column satisfies a specific condition 6) DEFAULT - Sets a default value for a column when no value is specified 7) INDEX - Used to create and retrieve data from the database very quickly.
Views: 20 R K
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: 19916 Caleb Curry
SQL Server 15 - Composite Key
 
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An interesting thing you can do with primary keys is that you can make a combination of columns the primary key. This is important when more than one column is required to make something unique. In an intermediary table, instead of having an association ID, we can have the combination of two rows as the primary key. This is known as either a compound or composite primary key. In the situation of using natural keys, composite keys are more common. For example, you could have a shopping website that allows multiple people from the same household to use a certain coupon you sent out. In this situation, you could use the address and the person's name as the natural primary key. What is the difference between a primary key and a column that has UNIQUE and NOT NULL constraints? The primary difference has to do with indexing. When you create a primary key, the column will automatically be indexed. This means that working with this data is faster. Now, we haven't talked a ton on indexes, but by default this will create a clustered index. UNIQUE constraints are also indexed by default, but the default index for a UNIQUE constraint is a non-clustered index. Clustered indexes determine how the table is actually stored, while non clustered indexes will make a sorted list that has reference to the data. This is not a life changing difference because these can actually be changed. We will discuss all of the details of indexing in future videos. As a side note, the IDENTITY column is not automatically indexed. How do we reference primary keys? This requires what is known as a foreign key, which we will discuss in the next video. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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: 9964 Caleb Curry
13.49 PRIMARY KEY, UNIQUE, FOREIGN KEY, REFERENCES, CONSTRAINT
 
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Komplette Liste der Videos und zusätzliches Material auf http://datenbankenlernen.de Informatik, Uni Saarland: Bachelor: http://www.cs.uni-saarland.de/index.php?id=52&L=1&source=1349 Master: http://www.cs.uni-saarland.de/index.php?id=132&L=1&source=1349 Ph.D./Grad School: http://gradschool.cs.uni-saarland.de/&source=1349
SQL: Foreign Key Creation
 
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In this tutorial, you'll learn how to create a foreign key column ....
Views: 41220 radhikaravikumar
Oracle||Oracle Integrity Constrants Patr -1 by Dinesh
 
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Oracle Tutorial || Oracle| Sql Constraints Part - 1 by basha
 
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SQL Server 28 - Composite Primary Key
 
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The previous video had these tables: CREATE TABLE Species( ID INT PRIMARY KEY IDENTITY, Species VARCHAR(50) NOT NULL UNIQUE, FriendlyName VARCHAR(50) NOT NULL ); CREATE TABLE Animals( ID INT PRIMARY KEY IDENTITY, Name VARCHAR(50) NOT NULL, Species INT NOT NULL REFERENCES Species(ID), ContactEmail VARCHAR(50) NOT NULL UNIQUE ); These column attributes are all examples of constraints. To be more specific, they are known as column-level constraints. Sometimes you need to create what is known as a table-level constraint. To illustrate this, we are going to create a new table that shows this in action. Remember that we are trying to create an animal dating site. A specific animal can create an account on our website and say what kind of species he or she is interested in. One specific animal can be interested in multiple species and an individual species can be liked by many animals. Therefore, it is a many to many relationship. We already have a Species table and an Animals table, so we need an intermediary table to associate animals with species: CREATE TABLE Interests( AnimalID INT NOT NULL REFERENCES Animals(ID), SpeciesID INT NOT NULL REFERENCES Species(ID) ); But now, we want to create a composite primary key, the combination of both columns. A column-level attribute is not capable of doing this because it is associated with just one column. Let's create a table-level constraint. To do this we add the constraint as if it's another column: CREATE TABLE Interests( AnimalID INT NOT NULL REFERENCES Animals(ID), SpeciesID INT NOT NULL REFERENCES Species(ID), PRIMARY KEY (AnimalID, SpeciesID) ); The downside here is that we cannot create a foreign key to reference this composite key. If for some reason we have to be able to reference an individual interest in another table, we would create an ID column and put a UNIQUE constraint on the combination of AnimalID and SpeciesID. Then we could reference an individual ID. Now, in SSMS, inside of our tables key folder you can find the composite key. Unfortunately, SSMS defaults to a pretty ugly name for our primary key constraint. Fortunately, we can actually give names to our constraints. That's what we will be doing in the next video. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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: 8917 Caleb Curry
Oracle - Primary Keys
 
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Oracle - Primary Keys
Views: 2717 Chris Ostrowski
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: 99278 Manish Sharma
PART 5.3 Indexing in dbms in hindi basics of indexing in dbms primary secondary clustered
 
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This video contains the basic concepts of Indexing and will help students in various competitive exams like GATE , NET, PSU'S etc indexing in dbms,indexing in dbms in hindi,indexing in database,indexing in database hindi,indexing in database gate,indexing in database management system,indexing in dbms example,indexing in dbms youtube,indexing in dbms for gate,indexing in sql,indexing in sql server,basics of indexing dbms,spanned and unspanned,sorted files in dbms,unsorted file in dbms,primary indexing and secondary indexing in dbms,clustered index vs nonclustered index indexing in dbms,indexing in dbms in hindi,indexing in database,indexing in database hindi,indexing in database gate,indexing in database management system,indexing in dbms example,indexing in dbms youtube,indexing in dbms for gate,indexing in sql,indexing in sql server,basics of indexing dbms,spanned and unspanned,sorted files in dbms,unsorted file in dbms,primary indexing and secondary indexing in dbms,clustered index vs nonclustered index indexing in dbms,indexing in dbms in hindi,indexing in database,indexing in database hindi,indexing in database gate,indexing in database management system,indexing in dbms example,indexing in dbms youtube,indexing in dbms for gate,indexing in sql,indexing in sql server,basics of indexing dbms,spanned and unspanned,sorted files in dbms,unsorted file in dbms,primary indexing and secondary indexing in dbms,clustered index vs nonclustered inde
Views: 157734 KNOWLEDGE GATE
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: 9873 R.N.A. Creation
Clustered and nonclustered indexes in sql server   Part 36
 
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In this video we will learn about 1. Different types of indexes in sql server 2. What are clustered indexes 3. What are NonClustered indexes 4. Difference between clustered and non clustered indexes Text version of the video http://csharp-video-tutorials.blogspot.co.uk/2012/09/clustered-and-non-clustered-indexes.html Slides http://csharp-video-tutorials.blogspot.com/2013/09/part-36-clustered-nonclustered-indexes.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: 458319 kudvenkat
Lec 06   Oracle Create table with composite Primary Key
 
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Oracle Create table with composite Primary Key
Views: 200 VTGAMES
Unique key constraint - Part 9
 
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In this video we will learn 1. What is unique key constraint 2. When do you use unique key constraint over primary key constraint 3. Difference between unique key constraint and primary key constraint Text version of the video http://csharp-video-tutorials.blogspot.com/2012/08/unique-key-constraint-part-9.html Slides http://csharp-video-tutorials.blogspot.com/2013/08/part-9-unique-key-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: 286458 kudvenkat
Oracle tutorial : How to create Id with AUTO INCREMENT in Oracle PL SQL
 
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Oracle tutorial: How to create Id with AUTO INCREMENT in Oracle oracle tutorial for beginners sequence in oracle identity key in sql In this Oracle tutorial , we can create an auto increment field using ‘sequence’ object that can be assigned as primary keys. Using Oracle ‘sequence’ object, you can generate new values for a column. An Oracle sequence is an object like a table or a stored procedure. Examples CREATE SEQUENCE SYSTEM.MYSEQ START WITH 1 MAXVALUE 999999999999999999999999999 MINVALUE 1 NOCYCLE CACHE 20 NOORDER; CREATE OR REPLACE TRIGGER TR_CITY BEFORE INSERT ON CITY FOR EACH ROW BEGIN SELECT LPAD(LTRIM(RTRIM(TO_CHAR(myseq.NEXTVAL))),10,'0') INTO :NEW.id FROM DUAL; END; / Subscribe on youtube: https://www.youtube.com/channel/UCpiyAesWNYOXSz5GPq8lbkA For more tutorial please visit #techquerypond https://techquerypond.wordpress.com https://twitter.com/techquerypond identity column
Views: 9331 Tech Query Pond
SQL Primary Key and Foreign Key with real life examples
 
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You Can Find the full course of 3 hours in a given link with 50% Coupon= https://goo.gl/g8SyVQ Learn SQL and Database Core Concepts: This SQL Tutorial will cover all Major SQL concepts from Scratch. SQL developers are earning higher salary in IT industry, but, its not about writing queries its about understanding and applying the right query at right time and this course will let you understand complex SQL Statements in an easy way . Moreover, This Course will teach you how to extract Data from Database and write complex queries to a database This course will focus on a wider scale by Covering Structure Query Language SQL concepts as a whole, whether Students work with MySQL, Microsoft SQL Server, Oracle Server, etc. Enroll Today! Lets start together. Jazeb Akram All Right Reserved https://www.Jazebakram.com https://twitter.com/jazebakram https://www.udemy.com/user/jazeb-akram/ https://goo.gl/g8SyVQ Coupon Code = 1YOUTUBE0
Views: 5911 Jazeb Akram
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 11G Tutorial | Intro to Primary and Unique Keys | InfiniteSkills Training
 
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Want all of our free Oracle videos? Download our free iPad app at http://itunes.apple.com/us/app/video-training-courses-from/id418130423?mt=8 http://www.infiniteskills.com/training/learning-oracle-database-11g.html In this Oracle 11G tutorial, you'll learn about primary and uniqe keys. The lesson is narrated by Lewis Cunningham, Oracle expert and author of the complete 8-hour course. YouTube: https://www.youtube.com/user/OreillyMedia Facebook: https://www.facebook.com/OReilly/?fref=ts Twitter: https://twitter.com/OReillyMedia Website: http://www.oreilly.com/

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