Design

• New software programs frequently require new databases. The database administrator may first discuss the program's design with software developers, users and managers. It addresses some major need for the organization, such as managing the Marketing department; the DBA examines its various requirements for data. She then draws up a design and uses database utility programs to construct the new database and the tables, fields and other objects in it.
  
  

Tuning

• A database may get relatively little use, or it may process millions of records every day. The more use it sees, the more important database tuning becomes. For example, the database fetches customer records by first searching for the customer account number. Usually, the database stores these numbers in a special file, called an index, in which they can be located quickly. Without the index, the database must look through all the customer records, one by one, bogging database activity down with needless searching. The database administrator may add new indexes to the database if they improve performance. Periodically, the DBA tests.the database to check its overall efficiency and fine-tunes it for best performance.
  
  

Maintenance

• Databases are dynamic things. New projects require additional tables and fields, users want data deleted or added and existing fields take on new purposes. The database administrator updates the structures as well as the data itself. When database vendors release new versions of their software, the DBA installs it. He makes a backup copy of the database, shuts down the old server software, installs the new software and performs a data conversion. He may test the various recordkeeping systems to make sure that users can access their data.
  
  

Security

• Relational databases provide many levels of security to accommodate different kinds of organizations. A DBA applies her knowledge of the database's security structure to address her organization's security needs. A small company, for example, may have only a few database users. A single password to access the whole database is usually enough; having too many only makes the database harder to use. A large company, on the other hand, has hundreds of database users. Managers might be granted more access than clerks; salespeople may be completely blocked from the payroll database. The database administrator, working with various department managers, creates a security scheme that gives people the access they need but no more.