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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: 8404 Caleb Curry
Oracle - SQL - Creating Index
 
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Oracle - SQL - Creating Index Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
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: 39063 TheSSScreations
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: 40807 Manish Sharma
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.
Indexes in sql server   Part 35
 
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In this video we will learn about What are indexes Why do we use indexes Advantages of indexes These concepts are applicable to sql server 2000, 2005 and 2008 Text version of the video http://csharp-video-tutorials.blogspot.com/2012/09/indexes-in-sql-server-part-35.html Slides http://csharp-video-tutorials.blogspot.com/2013/08/part-35-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: 375227 kudvenkat
SQL 11: Index Constraint
 
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Views: 200 gstevewall
Unique and Non Unique Indexes in sql server   Part 37
 
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In this video we will learn about 1. What is a Unique Index 2. Difference between unique index and unique constraint Text version of the video http://csharp-video-tutorials.blogspot.com/2012/09/unique-and-non-unique-indexes-part-37.html Slides http://csharp-video-tutorials.blogspot.com/2013/09/part-37-unique-non-unique-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: 205397 kudvenkat
Oracle - SQL - Not Null Constraint
 
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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.
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: 2003 Kishan Mashru
Index organised tables and heap tables, creating index organised tables
 
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Index organised tables and heap tables, creating index organised tables For Students of B.Tech, B.E, MCA, BCA, B.Sc., M.Sc., Courses - As Per IP University Syllabus and Other Engineering Courses
SQL: Indexes - Bit Map & B-trees
 
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In this tutorial, you'll learn when to use b-tree and bitmap index
Views: 53410 radhikaravikumar
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: 34291 Sam Dhanasekaran
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: 14639 Caleb Curry
Oracle Database Tutorial 63 : Introduction to Tablespace In Oracle Database
 
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Introduction to tablespace in oracle database consist Brief intro of tablepsace, type of tablespace, Big and small file tablespace, intro of Data files in oracle By manish sharma RebellionRider ------------------------------------------------------------------------ ►►►LINKS◄◄◄ Blog : http://bit.ly/tablespace-introduction-rebellionrider Previous Tutorial ► Indexes https://youtu.be/F5NrQYD4a9g ------------------------------------------------------------------------- ►►►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: 34884 Manish Sharma
4  When composite index would be used by Oracle
 
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If there is a composite index on any columns then will oracle use it if we give only few of these columns in where clause?
033-Oracle SQL Arabic Course - Index اوراكل ديفلوبر
 
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033-Oracle Developer SQL Arabic Course - Index Oracle Index .......................................­.................... تواصل معانا علي الفيس بوك من هنا : https://www.facebook.com/askgad .......................................­.................... تواصل معانا علي موقعنا من هنا : https://www.askgad.com/
Views: 1486 Ask Gad
Oracle Tutorial || online training||Adv Sql | Indexes Part - 1 by basha
 
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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: 288281 Voluntary DBA
oracle interview question oracle index and types of index
 
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Oracle Interview Question - oracle index related questions Description: Oracle Interview Question - oracle index related questions 1. What is Index? How to create index? 2. What are the types of index? 3. How to find the list of indexes for a given table? 4. Explain B-tree index 5. Explain Bitmap index 6. Explain "Function based" index 7. Explain "Reverse Key" index 8. When to choose what type of index? 9. How to know index is being used? 10. How to monitor index usage? 11. What are the advantages/drawbacks of indes? List of all the SQL and PLSQL interview questions @ https://easy-learning-tech.blogspot.com/p/oracle-sql-plsql-interview-questions.html
Views: 324 Siva Academy
Considerations around target side indexes and constraints
 
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A discussion around the best choices regarding designing the indexing and constraints on your target tables when using InfoSphere Data Replication
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: 458645 kudvenkat
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: 286625 kudvenkat
PART 5.7 Clustering Index | DBMS HINDI |
 
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This video contains the basic concepts of Clustering Index and will help students in various competitive exams like GATE , NET, PSU'S etc Following are the important topics of dbms ER‐model - entity–relationship model, strong entity set, weak entity set, single valued attribute, multivalued attribute, stored attribute, derived attribute, simple attribute composite attribute, weak relationship, strong relationship, mapping, cardinality ratios, discriminator attribute, fan trap, chasm trap Relational model – relational table, column, domain, row, tuple, relational algebra – selection, projection, union, intersection, set difference, Cartesian product, natural join, left outer join, right outer join, complete outer join, theta join, division operator, nested query, safe query tuple calculus – tuple relational calculus, domain relational calculus, SQL – select, from, where, order by, group by, max, min, avg, count, sum, having, Integrity constraints – super key, candidate key, primary key, foreign key, alternate key, secondary key, surrogate key normal forms – first normal form, second normal form, third normal form, bcnf, 4nf, 5nf, functional dependency, minimal cover, canonical collection, multivalued functional dependency, dependency preserving, lossy and lossless decomposition. File organization – indexing, B, B+ trees, key attribute, anchor attribute, primary indexing, secondary indexing, clustered indexing, multilevel indexing, block pointer, tree pointer, record pointer, top down search, sequential search, range query, index file, ordering, non-ordering Transactions and concurrency control- transaction, acid properties, atomicity, consistency, isolation, durability, life cycle of a transaction, active state, partially committed state, committed state, abort, rollback, terminated, phantom read, dirty read, unrepeatable read, lost update problem, conflict serializability, view serializability, irrecoverable schedule, cascading rollback, recoverable schedule, cascadless schedule. Lock based protocol, two phase locking, exclusive lock, shared lock, growing phase, shrinking phase, conservative two-phase locking, rigorous two phase locking, strict two phase locking, time stamping, time stamp, read, write, deadlock, granularity, tree based protocol,
Views: 73018 KNOWLEDGE GATE
Reorganizing Tables in Oracle
 
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The clip explains why reorganizing of tables may or may not be required and how to do it. Text version is here: https://uhesse.com/2010/08/23/reorganizing-tables-in-oracle-is-it-worth-the-effort/
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: 257802 Techtud
14.316 Covering and Composite Index, Duplicates, Overflow Pages, Composite Keys
 
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Video for my inverted classroom "Database Systems". The complete list of videos and additional material is (will be) available at http://datenbankenlernen.de Computer Science, Saarland University: Bachelor (in German): http://www.cs.uni-saarland.de/index.php?id=52&L=1 Master (in English): http://www.cs.uni-saarland.de/index.php?id=132&L=1 Ph.D./Grad School: http://gradschool.cs.uni-saarland.de/
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: 16976 Caleb Curry
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
Constraints In SQL | ORACLE
 
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This video explains you about constrains.
Views: 206 Online Pl Sql
Tutorial 43 : INDEX in Oracle || BITMAP INDEX.
 
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Hi Friends! Here we are learning about BITMAP Index. Help the concept is clear to you. Please give me your feedback in Comment Box. Thanks. Happy Coding.
Views: 131 YourSmartCode
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: 8100 Caleb Curry
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: 17094 Caleb Curry
Intuition Behind Oracle Index
 
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How index helps in performance For Full Course Experience Please Go To http://mentorsnet.org/course_preview?course_id=6 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: 13850 Oresoft LWC
B*Tree Index Fundamentals(Indexes in Oracle-1)
 
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Part -1 : Introduction to Indexes, B*Tree Indexes, Index scan methods. Part -2 : B*Tree Index Types(different types of B*Tree indexes) Part -3: Using B*Tree Indexes(When use B*Tree indexes, factors related to B*Tree Access) Part -4 : Index Organized Table Part -5 : Bitmap Indexes Part -6: Partitioned Indexes Part- 7: Other type of Indexes based on characteristics & use. Part -8: Managing Indexes
Views: 49083 Anindya Das
SQL Server Index Example in Tamil
 
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Click here to Subscribe to IT PORT Channel : https://www.youtube.com/channel/UCMjmoppveJ3mwspLKXYbVlg SQL Server Clustered & Non Clustered Index with example. Create index in a Table with bulk data, and Comparing Performance
Views: 3933 IT Port
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: 11748 Roland Martin
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: 15168 Caleb Curry
Working with Primary & Foreign key Constraint in SQL Server | SQL Server Tutorial
 
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Views: 58478 Naresh i Technologies
47. UNIQUE KEY in SQL (Hindi)
 
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Views: 18618 Geeky Shows
How can I speed up a query if an index cannot help?
 
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blog: connor-mcdonald.com Highlights from the April DBA Office Hours session. Office Hours is 100% free Q&A sessions held every month by Oracle experts to help you succeed with the Oracle suite of technologies. Music: Smells Like Summer - Del (Vlog Music No Copyrighted) Video Link: https://youtu.be/IrkMsqcOjGU
Views: 1187 Connor McDonald
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: 8937 Caleb Curry
Table Constraints in SQL: NOT NULL, DEFAULT, UNIQUE, and CHECK
 
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This SQL tutorial discusses the common constraints one can place on a table: NOT NULL, DEFAULT, UNIQUE, and CHECK, including the purpose of each constraint, as well as how to apply each constraint to a table during table creation. 0:24 NOT NULL Constraint 0:56 DEFAULT Constraint 2:03 UNIQUE Constraint 2:34 CHECK Constraint
Views: 8634 1Keydata
Top 30 PLSQL interview questions and answers
 
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Most frequently asked questions: How to get distinct entries from the database? How to get results of any query which is sorted in any order? What is a mutating table error and how can you get around it? Describe the use of %ROWTYPE and %TYPE in PL/SQL What packages (if any) has Oracle provided for use by developers?Describe the use of PL/SQL tables When is a declare statement needed ? In what order should a open/fetch/loop set of commands in a PL/SQL block be implemented if you use the %NOTFOUND cursor variable in the exit when statement? Why? What are SQLCODE and SQLERRM and why are they important for PL/SQL developers? How can you find within a PL/SQL block, if a cursor is open? How can you generate debugging output from PL/SQL? What are the types of triggers? What are two parts of package ? what is the difference between to_char and to_date functions? How do you optimize SQL queries ? What are nested triggers ? What is a bitmap index? What is the usage of NVL? write a query for finding the length of the sting. please explain database architecture. How to get employee name from employee table which is the fifth highest salary of the table? Write a query to generate target column. Can we use out parameter in function? What will be the output for the below Query Select 'High' from dual where null = null; what is the difference between stored procedure and packaged procedure What are the steps you take to tune(performance tuning) the code in plsql? what is self join and how it works?? Can you alter procedure with in package? What is substr()&instr()? Difference between case and decode? Can you use sysdate in check constraints? If no, why? Difference between column level constraints & table level constraints? What is optimizer? What is nested_loop join? What is pivot operator? Tell me some oracle 10g features? What is m_view? What is master & detail tables? What is sqlcode and sqlerrm? Diff b/w procedure & packages? What are the dis_adv of packages? How to retrieve top 3 salaries from each departments? Can you update complex view? If no, why? When should rebuild one an index? Tell me some errors? Tell me some restrictions on cursor variables? What is context switching? What is bulk collect? What is nullif()? What is mutating error? What are the module's , you are working? Which will fire default first statement level or row level trigger? What is bulkcollect? And any restrictions in bulkcollect? What is the use of limit clause in bulkcollect? How to debugg your code? How to trace error handling? How to find which line error was raised? What are the methods there in save exceptions? What is functional based index? Write syntax? How to update complex view? Subscribe here : https://www.youtube.com/channel/UCofhGV_j_4cVGa9R08MsuXQ
Views: 8739 Oracle PL/SQL

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