Understanding SQL

SQL Statement Categories

• �Data
• Definition Language (DDL) - �Statements
• used for creating tables, relationships, and other structures.
• �
• Data
• Manipulation Language (DML) - �Statements
• used for querying, inserting, modifying, and deleting data.
• �
• SQL /
• Persistent Stored Modules (SQL/PSM) - �These
• statements extend SQL by adding the ability to do procedural programming,
• including the use of variables and flow-of-control statements.
• �
• Transaction
• Control Language (TCL) - �Statements
• that control transaction behavior.
• �
• Data
• Control Language (DCL) - �Statements
• that grant or revoke permissions to users and groups so that those users and
• groups can perform operations on the database.

SQL - Framework

• �This
• is the most basic form of SQL queries.
• �
• SELECT: Selects the columns to be listed in the
• results of the query.��
• FROM: Specifies the tables to be used in the query.�
• WHERE: Specifies the rows that should be included in the results of the query.��