The users of a database system can be classified into various categories depending upon their interaction and degree of expertise of the DBMS.
1. End Users or Naive Users
The end users or naive users use the database system through a menu-oriented application program, where the type and range of response is always displayed on the screen. The user need not be aware of the presence of the database system and is instructed through each step. A user of an ATM falls in this category.
2. Online Users
These type of users communicate with the database directly through an online terminal or indirectly through an application program and user interface. They know about the existence of the database system and may have some knowledge about the limited interaction they are permitted.
3. Application Programmers
These are the professional programmers or software developers who develop the application programs or user interfaces for the naive and online users. These programmers must have the knowledge of programming languages such as Assembly, C, C++, Java, or SQL, etc., since the application programs are written in these languages.
4. Database Administrator
Database Administrator (DBA) is a person who have complete control over database of any enterprise. DBA is responsible for overall performance of database. He is free to take decisions for database and provides technical support. He is concerned with the Back-End of any project. Some of the main responsibilities of DBA are as follows :
- Deciding the conceptual schema or contents of database : DBA decides the data fields, tables, queries, data types, attributes, relations, entities or you can say that he is responsible for overall logical design of database.
- Deciding the internal schema of structure of physical storage : DBA decides how the data is actually stored at physical storage, how data is represented at physical storage.
- Deciding users : DBA gives permission to users to use Without having proper permission, no one can access data from database.
- Deciding user view : DBA decides different views for different users.
- Granting of authorities : DBA decides which user can use which portion of database. DBA gives authorities or rights to data access. User can use only that data on which access right is granted to him.
- Deciding constraints : DBA decides various constraints over database for maintaining consistency and validity in database.
- Security : Security is the major concern in DBA takes various steps to make data more secure against various disasters and unauthorized access of data.
- Monitoring the performance : DBA is responsible for overall performance of database. DBA regularly monitors the database to maintain its performance and try to improve it.
- Backup : DBA takes regular backup of database, so that it can be used during system Backup is also used for checking data for consistency.
- Removal of dump and maintain free space : DBA is responsible for removing unnecessary data from storage and maintain enough free space for daily He can also increase storage capacity when necessary.
- Checks : DBA also decides various security and validation checks over database to ensure consistency.
- Liaisioning with users : Another task of the DBA is to liaisioning with users and ensure the availability of the data they require and write the necessary external schemas.
Source: Gupta Satinder Bal, Mittal Aditya (2017), Introduction to Database Management System, 2nd Edition-University Science Press (2017)