Introducing SQL

This chapter provides an overview of SQL, including an introduction to interactive and embedded SQL statements. This chapter also describes the features and extensions of SQL and the database management system (DBMS).

SQL Functionality

SQL statements enable you to:

• Manipulate database objects—Create, modify, and destroy a variety of database objects, such as tables, views, indexes, and database procedures.
• Manipulate data—Select, insert, update, and delete data in database tables.
• Manage groups of statements as transactions—Process a group of database statements as a single transaction. Transaction management includes the ability to undo (roll back) a transaction, either in whole or in part.
• Perform other database management functions—Set runtime options, copy data between tables and files, modify the characteristics of a database table, and perform many other database management functions.

Types of SQL Statements

SQL statements are categorized according to the task performed:

• Data Definition Language (DDL)

  Creates or deletes objects such as tables, indexes, and database procedures.

• Data Manipulation Language (DML)

  Allows data manipulation in tables.