Managing Data Structures

Overview

In Oracle there are a number of types of data structures such as users, privileges, databases, tables, views, index and constraints. Oracle provides Data Definition Language (DDL) commands that are used to manipulate with data structures. Some examples:

• CREATE - to create objects in the database
• ALTER - to alter the structure of the database
• DROP - to delete objects from the database
• TRUNCATE - to remove all records from a table, including all spaces allocated for the records are removed
• COMMENT - to add comments to the data dictionary
• GRANT - to give user's access privileges to database
• REVOKE - to withdraw access privileges given with the GRANT command

In this chapter, we will introduce some useful DDL commands organized in the following sections:

• Managing Tables
• Managing Indexes
• Managing Views
• Managing Data Integrity
• Loading Data

Note that in general a DDL command executes and automatically commits. There is no way to reverse the changes of DDL command using ROLLBACK.