Database Users and Administrators

Database Users

The people who use the system are called users. Users can be categorized into those who actually use and manage the material (referred to as "Actors on the Scene") and those who make it possible to create the database and the DBMS software (referred to as "Workers Behind the Scene").

Users are put into different groups based on how they want to use the system. There are four different kinds of database users:

1. Naive Users:
   Naive users are people who don't know much about computers and use the system by calling up one of the application programs that have already been written. For example, a bank teller uses a program called "initaite_transfer" to move Rs. 15,000 from account A to account B. This program asks the teller for the amount of money that needs to be moved, the account that the money is coming from, and the account that the money is going to.
2. Application programmers:
   These are people who work in computers and write programs for applications. Application programmers have a lot of tools to choose from when making user interfaces. E.g., RAD (Rapid Application Development) tools let an application programmer make forms and reports without having to write a program.
3. Sophisticated users:
   These people know how to use the system without writing programs. They write their requests in a language for talking to databases. They send each query to a query processor, whose job is to turn DML statements into instructions that the storage manager can understand. This group is made up of analysts who use queries to look at data in the database.
   For example, Online Analytical Processing (OLAP) tools make analysts' jobs easier by letting them see data summaries in different ways. For example, analysts can see total products by categories, by no. of sales, or by a combination of categories and no. of sales.
4. Specialized users:
   Specialized users are advanced users who write database programs that don't fit into the traditional way of processing data. Among these applications are computer-aided design systems, knowledge base and expert systems, systems that store data with complex data types (like audio/visual data), and systems that model the environment.

Database Administrators

One of the main reasons to use DBMS is to have centralized control over both the data and the programs that access the data. The person in charge of the system as a whole is termed the database administrator (DBA). The following are some of the duties of the DBA:

1. Defining Schema:
   The DBA makes the original database schema by writing a set of definitions. The DDL compiler translates these definitions into a set of tables, which are then stored in the data dictionary.
2. Defining Storage Structure and Access Methods:
   The DBA makes the right storage structures and access methods by writing a set of definitions that the data-storage and data-definition language compiler translates.
3. Modification of Schema and Physical Organization:
   The DBA makes changes to the schema and physical organization to reflect how the organization's needs change or to change the physical organization to make it run better.
4. Giving Permission to Access Data:
   The database administrator can control which parts of the database different users can access by giving different types of permission. The information about who has permission to access the data is kept in a special system structure that is checked by the database system every time someone tries to access the data.
5. Fulfilling Integrity-Constraint Requirements:
   The values of the data stored in the database must meet certain consistency requirements. The database administrator must tell the database about this constraint. The integrity constraints are kept in a special structure that the database system checks every time it makes a change.
6. Regular Maintenance Tasks:
   DBA regularly needs to back up the database, either to tapes or to other servers, in order to avoid data loss in the event of emergencies. They also need to ensure that there is sufficient free disk space for standard operations and need to update disk space as necessary. DBA should also monitor database jobs to make sure performance is not harmed by extremely expensive tasks supplied by some users.