RSS
Twitter
Facebook
SQL can be divided into two
parts: The Data Manipulation Language (DML) and the Data Definition Language
(DDL).
The query and update commands
form the DML part of SQL:
• SELECT - extracts data from a
database
• UPDATE - updates data in a
database
• DELETE - deletes data from a
database
• INSERT INTO - inserts new data
into a database
The DDL part of SQL permits
database tables to be created or deleted. It also define indexes (keys), specify links between
tables, and impose constraints between tables. The most important DDL statements
in SQL are:
• CREATE DATABASE - creates a new
database
• ALTER DATABASE - modifies a
database
• CREATE TABLE - creates a new
table
• ALTER TABLE - modifies a table
• DROP TABLE - deletes a table
0 comments