SQL
SQL allows users to access data in relational database management systems, such as Oracle, Sybase, Informix, Microsoft SQL Server, Access, and others, by allowing users to describe the data the user wishes to see. SQL also allows users to define the data in a database, and manipulate that data.
Although SQL is defined by both ANSI and ISO, there are many extensions to and variations on the version of the language defined by these standards bodies. Many of these extensions are of a proprietary nature, such as Oracle Corporation's PL/SQL or Sybase, IBM's SQL PL (SQL Procedural Language) and Microsoft's Transact-SQL.
SQL is not case sensitive.
Standard SQL statements can be subdivided into 4 distinct groups which are shown below:
| Group |
Statements |
| DQL (Data Query Language) |
Select |
| DML (Data Manipulation Language) |
Delete, Insert, Update |
| DDL (Data Defination Language) |
DROP, TRUNCATE, CREATE, ALTER |
| DCL (Data Control Language) |
REVOKE,GRANT |
