Typically there are three types of users for a DBMS. They are :

1. The End User who uses the application. Ultimately, this is the user who actually puts the data in the system into use in business. This user need not know anything about the organization of data in the physical level. She also need not be aware of the complete data in the system. She needs to have access and knowledge of only the data she is using.
2. The Application Programmer who develops the application programs. She has more knowledge about the data and its structure since she has manipulate the data using her programs. She also need not have access and knowledge of the complete data in the system.
3. The Database Administrator (DBA) who is like the super-user of the system. The role of the DBA is very important and is defined by the following functions.

• Defining the Schema

  The DBA defines the schema which contains the structure of the data in the application. The DBA determines what data needs to be present in the system ad how this data has to be represented and organized.

• Liaising with Users

  The DBA needs to interact continuously with the users to understand the data in the system and its use.

• Defining Security & Integrity Checks

  The DBA finds about the access restrictions to be defined and defines security checks accordingly. Data Integrity checks are also defined by the DBA.

• Defining Backup / Recovery Procedures

  The DBA also defines procedures for backup and recovery. Defining backup procedures includes specifying what data is to backed up, the periodicity of taking backups and also the medium and storage place for the backup data.

• Monitoring Performance

  The DBA has to continuously monitor the performance of the queries and take measures to optimize all the queries in the application.