1. The database administrator is a person having central control over data and programs accessing that data. Duties of the database administrator include:

• Scheme definition: the creation of the original database scheme. This involves writing a set of definitions in a DDL (data storage and de nition language), compiled by the DDL compiler into a set of tables stored in the data dictionary.
• Storage structure and access method definition: writing a set of definitions translated by the data storage and de nition language compiler.
• Scheme and physical organization modification: writing a set of definitions used by the DDL compiler to generate modi cations to appropriate internal system tables (e.g. data dictionary). This is done rarely, but sometimes the database scheme or physical organization must be modified.
• Granting of authorization for data access: granting di erent types of authorization for data access to various users.
• Integrity constraint specification: generating integrity constraints. These are consulted by the database manager module whenever updates occur.