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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: 9773 Caleb Curry
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.
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 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: 12495 Caleb Curry
4- Oracle DB - Primary Foreign Unique Not Null Check Composite Keys Table Level and Column Level.avi
 
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Oracle DB - Primary Foreign Unique Not Null Check Composite Keys Table Level and Column Level
Views: 2704 Adel Sabour
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: 218232 kudvenkat
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: 23757 Caleb Curry
Constraints Part-2 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: 32 R K
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: 8886 1Keydata
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: 46 R K
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: 2390 Kishan Mashru
Primary Key,Unique Key ,Null Key  in SQL
 
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A primary key is a field in a table which uniquely identifies each row/record in a database table. Primary keys must contain unique values. A primary key column cannot have NULL values. A table can have only one primary key, which may consist of single or multiple fields.
Views: 69 ANKUSH THAVALI
47. UNIQUE KEY in SQL (Hindi)
 
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Please Subscribe Channel Like, Share and Comment Visit : www.geekyshows.com
Views: 22631 Geeky Shows
T-SQL - NOT NULL Constraints
 
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T-SQL - NOT NULL Constraints Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited
oracle interview question oracle index function based index
 
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Title: Oracle Interview Question - oracle index related questions - Function based index in oracle 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 indexes?
Views: 655 Siva Academy
Oracle Database | Bangla Tutorials 24 :: Constraint Unique Key
 
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www.facebook.com/oracle.shohag Email : [email protected] Website : www.oraclebangla.com Topics : Constraint Unique Key
Views: 1027 Oracle Bangla
SQL Server 26 - PRIMARY KEY, NOT NULL, UNIQUE
 
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In the last video we created our first table, but I want to give SQL Server some extra information so the database knows more about each of the columns. The first thing is to establish the primary key. To do this all we do is add PRIMARY KEY after the column we want to be the primary key. Simple enough. When we add a constraint right after the column like this, it is often called a column attribute. CREATE TABLE Animals( ID INT PRIMARY KEY, Name VARCHAR(50), Species VARCHAR(50) ); Additionally, if you are using an ID column, it is best to have it labeled as the IDENTITY column. That way, SQL Server will automatically increment the number. CREATE TABLE Animals( ID INT PRIMARY KEY IDENTITY, Name VARCHAR(50), Species VARCHAR(50) ); The other attributes we've discussed in this series are NOT NULL and UNIQUE. We can make the name NOT NULL and the species NOT NULL. We don't have a good column for UNIQUE, so let's add one: CREATE TABLE Animals( ID INT PRIMARY KEY IDENTITY, Name VARCHAR(50) NOT NULL, Species VARCHAR(50) NOT NULL, ContactEmail VARCHAR(50) NOT NULL UNIUQE ); You can see that it is very easy to add multiple column attributes to a column. Just separate them by spaces. The order does not matter. Also, when you say primary key the column is automatically NOT NULL and UNIQUE. There are other attributes you can use including DEFAULT, FOREIGN KEY, and SPARSE. DEFAULT will give a value for a column if you do not put anything in yourself. Foreign keys are used to reference other columns. SPARSE is an attribute we haven't discussed. You can use SPARSE if most of the rows are going to have a NULL for a column and it saves storage space, but we will worry about that in another 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: 5830 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.
NOT NULL, DEFAULT, CHECK Constraints (Domain Integrity) in SQL Server
 
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NOT NULL, DEFAULT, CHECK Constraints (Domain Integrity) in SQL Server Check my blog for more on Constraints and related sample SQL Queries: http://sqlwithmanoj.com/2010/11/23/integrity-constraints/ Check the whole "SQL Server Basics" series here: https://www.youtube.com/playlist?list=PLU9JMEzjCv14f3cWDhubPaddxRvx1reKR Check my SQL blog at: http://sqlwithmanoj.com/ Check my SQL FB Page at: https://www.facebook.com/sqlwithmanoj
Views: 16341 SQL with Manoj
UNIQUE AND NON-UNIQUE INDEX IN SQL (URDU / HINDI)
 
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SUBSCRIBE FOR MORE AND PRESS BELL ICON TO GET LATEST VIDEO UPDATES...
Views: 495 Learning Never Ends
Oracle SQL Tuning with NOT NULL Constraints
 
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Learn how to tune SQL with Constraints! In this lesson (3 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: 407 SkillBuilders
Oracle Database | Bangla Tutorials 23 :: Constraint Not null
 
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www.facebook.com/oracle.shohag Email : [email protected] Website : www.oraclebangla.com Topics : Constraint Not null
Views: 1036 Oracle Bangla
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.
A case study on using Composite Unique Indexes in Oracle on nullable columns
 
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We use unique indexes in Oracle to maintain distinct values in columns. Let us explore a case where we have Unique Indexes on(combination of) two or more columns in a table in Oracle, where one column has mostly null values.
Views: 7 Peeush Trikha
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: 197 Tech Query Pond
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 - 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 - 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.
mysql tutorial for beginners (6/8) : Indexes
 
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mysql tutorial for beginners (6/8) : Indexes As things stand, the table students works and can be searched without problem by MySQL—until it grows to more than a couple of hundred rows, At that point, database accesses will get slower and slower with every new row added, because MySQL has to search through every row whenever a query is issued. This is like searching through every book in a library whenever you need to look something up. Of course, you don’t have to search libraries that way, because they have either a card index system or, most likely, a database of their own. The way to achieve fast searches is to add an index, either when creating a table or at any time afterward. But the decision is not so simple. For example, there are different index types such as a regular INDEX, PRIMARY KEY, and FULLTEXT. Also, you must decide which columns require an index, a judgment that requires you to predict whether you will be searching any of the data in that column. And even when you’ve decided that, you still have the option of reducing index size by limiting the amount of each column to be indexed. If we imagine the searches that may be made on the students table, it becomes apparent that all of the columns may need to be searched. Anyway, go ahead and add an index to each of the columns, using the commands: ALTER TABLE students ADD INDEX(name(3)); An alternative to using ALTER TABLE to add an index is to use the CREATE INDEX command. They are equivalent, except that CREATE INDEX cannot be used for creating a PRIMARY KEY CREATE INDEX surname ON students (surname(5)); DESCRIBE students; These commands create indexes on both the name and surname columns, limiting name index to only the first 3 characters, and surname index to the first 5 characters. For instance, when MySQL indexes the following name: SAFAA It will actually store in the index only the first 3 characters: SAF This is done to minimize the size of the index, and to optimize database access speed. DESCRIBE command shows the key MUL for each column. This key means that multiple occurrences of a value may occur within that column, which is exactly what we want, as name or surname may appear many times. You don’t have to wait, until after creating a table to add indexes. In fact, doing so can be time-consuming, as adding an index to a large table can take a very long time. Therefore, let’s look at a command that creates the table students with indexes already in place. CREATE TABLE students ( Id_studnet SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT, name VARCHAR(10) NOT NULL, surname VARCHAR(20) NOT NULL, email VARCHAR(30) NOT NULL, INDEX(name(3)), INDEX(surname(5)), ,PRIMARY KEY(id_studnet),UNIQUE(email)); Another important index, PK, its single unique key for each student to enable instant accessing of a row. The importance of having a key with a unique value for each row will come up when we start to combine data from different tables. You can add PK, while you create the table at the first time, or later by issuing the following command: ALTER TABLE students ADD PRIMARY KEY(id_student); The last important index, FULLTEXT index Unlike a regular index, MySQL’s FULLTEXT allows super-fast searches of entire columns of text. It stores every word in every data string in a special index that you can search using “natural language,” in a similar manner to using a search engine. It’s not strictly true that MySQL stores all the words in a FULLTEXT index, because it has a built-in list of more than 500 words that it chooses to ignore because they are so common that they aren’t very helpful for searching anyway. This list, called stopwords, includes the, as, is, of, and so on. The list helps MySQL run much more quickly when performing a FULLTEXT search and keeps database sizes down. FULLTEXT indexes can be created for CHAR, VARCHAR, and TEXT columns only. A FULLTEXT index definition can be given in the CREATE TABLE statement when a table is created, or added later using ALTER TABLE (or CREATE INDEX). Adding a FULLTEXT index to the table students for the columns name and surname ALTER TABLE classics ADD FULLTEXT(name,surname); this index is in addition to the ones already created and does not affect them You can now perform FULLTEXT searches across this pair of columns. If you find that MySQL is running slower than you think it should be when accessing your database, the problem is usually related to your indexes. Either you don’t have an index where you need one, or the indexes are not optimally designed. Tweaking a table’s indexes will often solve such a problem. In the next tutorial, we will learn about, using FOREIGN KEY Constraints and how to join tables together. Subscribe for more: ---------------------------------------------------------------------------- https://www.youtube.com/subscription_center?add_user=saf3al2a SWE.Safaa Al-Hayali - saf3al2a
Views: 30291 Safaa Al-Hayali
Understanding Primary Key, Unique and Null Constraints
 
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In this video discusses Null, Unique and Primary Key constraints of SQL. It also covers demonstration of these constraints in Oracle.
4 - T-SQL - CONSTRAINTS (Restrições) - PRIMARY KEY, NOT NULL, etc - SQL Server
 
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T-SQL - CONSTRAINTS (Restrições) Neste vídeo vamos mostrar como configurar as constraints PRIMARY KEY, NOT NULL, UNIQUE, FOREIGN KEY, CHECK, DEFAULT ao criarmos tabelas em bancos de dados com SQL Server Contribua com a Bóson Treinamentos!: Como contribuir: http://www.bosontreinamentos.com.br/contribuir/ Por Fábio dos Reis Bóson Treinamentos: http://www.bosontreinamentos.com.br Facebook: https://www.facebook.com/bosontreinamentos/ Pinterest: https://br.pinterest.com/bosontreina/ Twitter: https://twitter.com/bosontreina Instagram: https://www.instagram.com/bosontreinamentos/ LInkedin: https://www.linkedin.com/in/f%C3%A1bio-dos-reis-06ba192a/ Outros projetos do autor: Diário do Naturalista: http://www.diariodonaturalista.com.br
Views: 44346 Bóson Treinamentos
Oracle interview question difference between null functions
 
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Difference between NVL,NVL2, NULLIF and COALESCE NVL function will check whether the first input parameter is null, if first input parameter is null then the function returns the second parameter value as output. NVL2 function will check the first parameter, and return second parameter if the first parameter is not null, otherwise returns third parameter. NULLIF will compare the input parameters ( first and second parameter ), and returns NULL of both are same, otherwise returns the first parameter value. COALESCE, returns the first not null expression in the given input parameters. -------------------------------------------------------------------------------------------------------- List of all the SQL and PLSQL interview questions https://easy-learning-tech.blogspot.com/p/oracle-sql-plsql-interview-questions.html
Views: 1419 Siva Academy
Oracle SQL Tutorial For Beginners | Oracle SQL Online Training - Session 1
 
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Course : Oracle SQL Online Training Mode of Training : Online Duration : 40 Hours Timings : Flexible Oracle SQL Online Training Demo Registration Link : http://svsoftsolutions.com/demo.aspx Introduction to SQL What is SQL? What Can SQL do? RDBMS SQL Syntax Database Tables SQL Statements Overview of Most Important SQL Commands SELECT UPDATE DELETE INSERT CREATE TABLE ALTER TABLE DROP TABLE CREATE INDEX DROP INDEX SQL SELECT Statement SELECT syntax Demo Database SELECT Column Example SELECT * Example SQL Distinct SELECT DISTINCT Statement SELECT DISTINCT Syntax SELECT DISTINCT Example SQL WHERE Clause WHERE Clause WHERE Clause Example Operators in the WHERE Clause SQL AND & OR Operators AND Operator Example OR Operator Example Combining AND & OR SQL ORDER BY ORDER BY Syntax ORDER BY Example ORDER BY DESC Example ORDER BY Several Column Examples SQL Insert Into INSERT INTO Syntax INSERT INTO Examples Insert Data into Specified Columns SQL UPDATE UPDATE Syntax UPDATE Example Watch out UPDATE statement. SQL DELETE DELETE Syntax DELETE Examples Delete All the Data SQL Aliases SQL Alias Syntax for Columns Alias Example for Table Columns Alias Example for Tables. SQL Joins Different SQL JOINs INNER JOIN LEFT OUTER JOIN RIGHT OUTER JOIN FULL OUTER JOIN SQL UNION UNION Syntax UNION Example UNION ALL Syntax UNION ALL Example SQL Insert Into Select INSERT INTO SELECT Syntax INSERT INTO SELECT Examples SQL Create Table CREATE TABLE Syntax CREATE TABLE Example SQL Constraints CREATE TABLE + CONSTRAINT Syntax NOT NULL Constraint UNIQUE Constraint UNIQUE Constraint on CREATE TABLE UNIQUE Constraint on ALTER TABLE To DROP a UNIQUE Constraint PRIMARY KEY Constraint PRIMARY KEY Constraint on CREATE TABLE PRIMARY KEY Constraint on ALTER TABLE To DROP a PRIMARY KEY Constraint FOREIGN KEY Constraint FOREIGN KEY Constraint on CREATE TABLE FOREIGN KEY Constraint on ALTER TABLE To DROP a FOREIGN KEY Constraint CHECK Constraint CHECK Constraint on CREATE TABLE CHECK Constraint on ALTER TABLE To DROP a CHECK Constraint DEFAULT Constraint on CREATE TABLE DEFAULT Constraint on ALTER TABLE To DROP a DEFAULT Constraint SQL Create Index CREATE INDEX Syntax CREATE UNIQUE INDEX Syntax CREATE INDEX Example SQL DROP Command The DROP INDEX Statement The DROP TABLE Statement The DROP DATABASE Statement The TRUNCATE TABLE Statement SQL ALTER Command The ALTER TABLE Statement ALTER TABLE Example Change Data Type Example DROP COLUMN Example SQL VIEWS CREATE VIEW Statement CREATE VIEW Syntax CREATE VIEW Examples CREATE OR REPLACE VIEW Syntax Dropping a View SQL NULL Values Working with NULL Values IS NULL IS NOT NULL SQL NULL Functions NVL COALESCE For more details visit our website : www.svsoftsolutions.com Or reach us @ USA : +1-845-915-8712 (Toll Free), India : +91-9642373173
Views: 2806 SV Soft Solutions
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: 17227 Caleb Curry
Oracle - SQL - Creating Sequences
 
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Oracle - SQL - Creating Sequences Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
How to create Foreign Key Constraint on Multiple Columns in SQL Server - SQL Server Tutorial Part 67
 
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SQL Server / TSQL Tutorial Scenario: You are working as SQL Server developer, you need to create a table dbo.Customer with composite primary key by using columns FName and SSN. One you are done with creating primary key in dbo.Customer table, you need to create second table dbo.Orders and create foreign key constraint by using Primary Key columns. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-create-foreign-key-constraint-on.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 5418 TechBrothersIT
Part 4   Delete duplicate rows in sql
 
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Link for all dot net and sql server video tutorial playlists http://www.youtube.com/user/kudvenkat/playlists Link for slides, code samples and text version of the video http://csharp-video-tutorials.blogspot.com/2014/05/part-4-delete-duplicate-rows-in-sql.html In this video, we will discuss deleting all duplicate rows except one from a sql server table. SQL Script to create Employees table Create table Employees ( ID int, FirstName nvarchar(50), LastName nvarchar(50), Gender nvarchar(50), Salary int ) GO Insert into Employees values (1, 'Mark', 'Hastings', 'Male', 60000) Insert into Employees values (1, 'Mark', 'Hastings', 'Male', 60000) Insert into Employees values (1, 'Mark', 'Hastings', 'Male', 60000) Insert into Employees values (2, 'Mary', 'Lambeth', 'Female', 30000) Insert into Employees values (2, 'Mary', 'Lambeth', 'Female', 30000) Insert into Employees values (3, 'Ben', 'Hoskins', 'Male', 70000) Insert into Employees values (3, 'Ben', 'Hoskins', 'Male', 70000) Insert into Employees values (3, 'Ben', 'Hoskins', 'Male', 70000) The delete query should delete all duplicate rows except one. Here is the SQL query that does the job. PARTITION BY divides the query result set into partitions. WITH EmployeesCTE AS ( SELECT *, ROW_NUMBER()OVER(PARTITION BY ID ORDER BY ID) AS RowNumber FROM Employees ) DELETE FROM EmployeesCTE WHERE RowNumber ] 1
Views: 357505 kudvenkat
Advantages and disadvantages of indexes in sql server   Part 38
 
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In this video we will learn about 1. Advantages and disadvantages of indexes 2. The types of queries that can benefit from indexes 3. Covering Queries Text version of the video http://csharp-video-tutorials.blogspot.com/2012/09/advantages-and-disadvantages-of-indexes.html Slides http://csharp-video-tutorials.blogspot.com/2013/09/part-38-adv-dis-adv-of-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: 167510 kudvenkat
Oracle Database Bangla Tutorials 21 :: Constraint Primary key
 
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www.facebook.com/oracle.shohag Email : [email protected] Website : www.oraclebangla.com Topics : Constraint Primary key
Views: 1488 Oracle Bangla
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: 12255 ITORIAN
MySQL - phpMyAdmin 4.5.1 Add UNIQUE Constraint To Existing Column
 
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Mysql statement Alter Table to adding a UNIQUE Constraint key to an existing column to avoid duplicate rows
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: 48425 Caleb Curry
Oracle PL SQL interview question NULL and Order by Clause
 
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Oracle PL SQL interview question NULL and Order by Clause Click here to subscribe to my youtube channel http://www.youtube.com/channel/UCBt6VrxAIb5jLh9HLDcdwtQ?sub_confirmation=1 Oracle Interview questions and Answers at https://www.youtube.com/playlist?list=PLb1qVSx1k1Vr0v4wVyvT3GEuA0J0M4xBm Oracle 18C New features at https://www.youtube.com/playlist?list=PLb1qVSx1k1Vqe06V1tIBcvnslMPWX69bW Oracle 12C New features at https://www.youtube.com/playlist?list=PLb1qVSx1k1VqM1u2IHWzZIgziqejl6wx- Oracle PLSQL records and collections at https://www.youtube.com/playlist?list=PLb1qVSx1k1VpAFTXopXvAh_D3PLcTntdm
Views: 463 Siva Academy
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: 301179 kudvenkat
Oracle Sql Step by Step Approach (041 how are null values treated while sorting data)
 
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Oracle Sql Step by Step Approach (041 how are null values treated while sorting data) Discover essential SQL skills necessary to transform you into SQL developer which can earn you $70k+ in the IT Industry Learn to become a fee-earning SQL developer in just seven weeks. This fast, easy and effective course will take you from zero sql writing skills to being able to make money as a SQL developer. This one-stop-shot-style SQL course will teach you everything you need to know about SQL, from learning various database concepts to writing SQL to interact with the database. Throughout this SQL course I will be using the below methodology to make you think and help in forming the SQL statement. Like,Comment,Share
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: 20399 Oresoft LWC
How to Install Oracle! !! Database Training
 
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For Complete Database Training Details Visit: http://www.qaonlinetraining.com http://infotek-solutions.com/ Delivery Method: Instructor led classroom and Online Training supported by world class Learning management system which automate all flow of lectures, videos, assignments, forums, quizzes and interview process. Class Schedule: Week-ends and Weekdays Contact Us: 571-437-0652, Mail Us: [email protected] Training Locations at : Ashburn / Fairfax / Maryland Office Address: 12801 Worldgate Dr #500, Herndon, VA 20170 Overview of Oracle DBA Training Oracle as a flexible, complex & robust RDBMS The evolution of hardware and the relation to Oracle Different DBA job roles (VP of DBA, developer DBA, production DBA, database babysitter) The changing job role of the Oracle DBA Environment management (network, CPU, disk and RAM) Instance management (managing SGA regions) Oracle table and index management Instance Architecture Instance vs. database Components of an instance Creating the OFA file structure ($DBA, bdump, udump, pfile) Oracle Instance Internals SGA vs. PGA Background processes Interfaces with server and disk I/O subsystem Using SQL*Plus for DBA management Connecting and executing SQL Using the “as sysdba” syntax Overview of SQL*Plus DBA commands (startup, etc.) Control file, UNDO and REDO management Explaining the use of control files Listing the Contents of the control File File locations for control Files Obtaining Control File Information Listing control file contents Displaying and Creating Undo segments Altering Undo Segments Determining the Number and Size of Undo segments Understanding flashback technology Troubleshooting Undo – snapshot too old Redo log concepts for recovery Online redo log (log_buffer) online redo logs and archived redo logs Oracle ARCH and LGWR background processes Redo log dictionary queries Redo log switch frequency and performance Multiplexing the Online Redo Log Files Archiving the Oracle Redo Logs Recovery using the redo log files User and privilege management The three security methods (VPD, Grant security/role-based security, grant execute) Creating New Database Users Using pre-spawned Oracle connections Auditing User activity Identifying System and Object Privileges Granting and Revoking Privileges Creating and Modifying Roles Displaying user security Information from the Data Dictionary Overview of instance management Parameter files (init.ora, listener.ora, tnsnames.ora) Rules for sizing SGA components Automated Oracle memory management (AMM) Initialization file management Creating the init.ora file Using spfile Displaying init.ora values with v$parameter Oracle*Net configuration Creating the listener.ora file Creating the tnsnames.ora file Data buffer configuration & sizing Inside the Oracle data buffers Using the KEEP pool Monitoring buffer effectiveness Using multiple blocksizes (multiple buffer pools) Shared pool and PGA configuration & Sizing Shared pool concepts and components Understanding the library cache Relieving shared pool contention Overview of PGA for sorting and hash joins Using sort_area_size, hash_area_size and pga_aggregate_target Troubleshooting network connectivity Verifying network connectivity with ping and tnsping Testing database links Oracle tables, views and materialized views Types of Oracle tables (regular, IOT, sorted hash clusters, nested tables) Oracle Views Oracle materialized views Oracle indexes Types of Oracle indexes (b-tree, bitmap, bitmap join index) Creating B*-Tree, bitmap and function-based Indexes Function-based indexes Finding indexing opportunities Index maintenance Oracle constraints Costs & benefits of constraints Types of Oracle indexes constraints (check, not null, unique, PK, FK) Cascading constraints Schema, File & tablespace management Describing the relationship between data files, tablespaces and table Understanding Oracle segments Creating Tablespaces – using the autoextend option Changing the Size of Tablespaces – alter database datafile command Defining a TEMP tablespace Changing the default storage Settings for a tablespace Review of the storage parameters in DBA views (ASM, ASSM, pctfree, pctused and freelists). Monitoring Chained rows (fetch continued rows) Monitoring Insert and Update performance (pctused, APPEND) Database Maintenance Reason for reorgs – chained rows, imbalanced freelists Reorganizing Tables using Export and Import Using CTAS to reorganize data Index rebuilding Backup & Recovery overview (hot & cold Backups, RMAN, block change tracking) Oracle DBA Utilities Data pump (Imp and exp utilities) SQL*Loader LogMiner Flashback DataGuard Oracle DBA utilities – Oracle dbms packages (dbms_redefinition)
How to create Unique Constraint on Multiple Columns in SQL Server - SQL Server/TSQL Tutorial Part 96
 
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SQL Server / TSQL Tutorial Scenario: If you have noticed the insert statement, In First Record I have put both Null values for FirstName and Last Name. In 2nd record I used the value 'Aamir' for first name and Null for Last Name. In 3rd record vice versa of 2nd record. From here what we understand that the unique constraint is working on both column values. As long as the combined value from both columns is unique, it is going to let us insert even one of them is null. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/05/how-to-create-unique-constraint-on.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 2566 TechBrothersIT

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