SQL 2012

SQL(Structure Query Language)


What is SQL?


SQL stands for Structured Query Language. SQL is used to communicate with a database. According to ANSI (American National Standards Institute), it is the standard language for relational database management systems. 

SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database. Some common relational database management systems that use SQL are: Oracle, Sybase, Microsoft SQL Server, Access, Ingres, etc.

 This language was developed by IBM in 1970s.


Types of SQL Statements:-

The Sql Statements can be divided into the following categories.

Data Definition Language (DDL):-
Is used to define the database, data types, structures, and constraints on the data. Some of the DDL statements are:-

Create:-
Used to create a new database object, such as table.

Alter:-
Used to modify the database objects.

Drop:-
Used to delete the objects.

Data Manipulation Language (DML):-
Is used to manipulate the data in database objects. Some of the DML statements are:-

Insert:-
Used to insert a new data record in a table.

Update:-
Used to modify an existing record in a table.

Delete:-
Used to delete a record from a table.

Data Control Language(DCL):-
Is used to control the data access in the database. Some of the DCL statements are:-

GRANT:-
Used to assign permissions to users to access a database object.

Revoke:-
Used to deny permissions to users to access a database object.

Data Query Language(DQL):-
Is used to query data from database objects. Select is the DQL statement that is used to select data from the database in different ways and formats.

SQL is not a case sensitive language.


Identifying Data Types:-

  1. Numeric
  2. Character String
  3. Date and Time
  4. Binary
  5. Others


Numeric:-
The numeric data types allow you to store integer values in the database. The following table lists the numeric data types supported by sql server.




Character and String:-
The character and string data types allow you to store text values in the database.





Data and Time:-
The date and time data types allow you to store date and time values in the database.



Binary:-
The binary data types allow you to store binary data in the database.



Others:-
The other data types allow you to store unique identifiers, cursors, table, XML, and spatial data in the database.




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