A data definition also known as data description language ( DDL ) is a language used for
Question:
A data definition also known as data description language (DDL) is a language used for defining data structures for database schemas. DDL statements create, modify, and delete database objects such as tables, views, indexes, procedures, and users. Commonly used DDL statements are CREATE (creating new objects), ALTER (modifying existing objects), and DROP (deleting objects).
The system catalog tables that keep track of database metadata such as tables information, are modified or entered through DDL statements. The system catalog entities are read-only and cannot be modified by the database user or administrator. They also keep track of which objects are accessible to database users to modify the user objects.
The metadata contains definitions of records, data items and other objects that are used by the DBA or developers to get more information about the DBMS. The DBMS refers to the system catalog before the data is accessed within the database. System catalog is also referred as data dictionary which is used to describe the. DDL to manage all the database objects in a DBMS.
If you have accidentally executed a DDL command, can it be rolled backed? Explain your reasoning?
Modern Systems Analysis And Design
ISBN: 9781292351629
9th Global Edition
Authors: Joe Valacich, Joey George