SQL Overview
Structured Query Language (SQL):
SQL stands for Structured Query Language; SQL interacts with the database on the server-side. It is a standard language for accessing and manipulating databases; it includes database creation, deletion, updation, fetching rows, modifying rows, tables, stored procedures (SP’s), execute queries, retrieve, insert data against a database. SQL is an American National Standard Institute (ANSI) standard.
Relational Database System
- SQL keywords are not case sensitive.
- MS SQL Server using T-SQL
- Oracle using PL/SQL
- MS Access version of SQL is called JET SQL etc.
SQL commands to interact with relational databases system are presented like - CREATE, SELECT, INSERT, UPDATE, DELETE and DROP. SQL commands can be classified into the following types:
SQL commands
- DDL – Data Definition Language
- DML – Data Manipulation Language
- DQL – Data Query Language
- DCL – Data Control Language
- TCL – Transaction Control Language
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SQL Commands Description
| Type |
Description & Commands |
| DDL |
Allows to work with the Structure or Definition of the data. SQL commands: CREATE, ALTER, DROP, TRUNCATE, COMMENT, RENAME |
| DML |
To deal with the data itself directly. And SQL Commands: INSERT, UPDATE, DELETE |
| DQL |
Deals with the data but to retrive the data. SQL Commands: SELECT |
| DCL |
Controls the data. SQL Commands: GRANT, REVOKE, DENY |
| TCL |
Deals with the transaction management. SQL Commands: COMMIT, ROLEBACK, SAVE |