What is a database administrator?
A database administrator (DBA):
- makes sure his databases are working without failure.
- is responsible for his databases’ security. Example: the administrator decides who in the company has the right to do actions in theses databases.
- has the right to do all actions in his databases.
- backs up his databases regularly.
- installs and configures new databases.
Can you give an example of database failure?
We saw that a database resides on a hard drive. A hard drive can break. A hard drive has limited space, so it can be full (no more place left).
We also saw that the DBMS is a software. Like any other software, it can lack memory and can become very slow or even stop functioning. Worse, it can make some documents unusable.
What does backing up the database mean?
This means saving a copy of the database in a safe place. In case of disaster, the database administrator uses this copy to restore the database. Restoring the database means putting back the database in the same state as before something bad happened.
What do you mean by giving rights?
In a database, you can update, retrieve and delete information. You can also modify the structure of the database by creating or modifying tables.
If a company owns a database, it cannot let anybody do all these actions on this database. For example:
- it cannot let the competition see information about its clients.
- it cannot let sales persons modify information about sales results.
- it cannot let any employee delete tables.
To prevent such unwanted actions:
- a database administrator assigns to each employee a username and password.
- before he can use a database, a user must choose the database he wants to use and enter his username and password.
- the database administrator decides, for each user, what this user can or cannot do.
The ability to do an action on a database is called a privilege or a right. Taking off a right is also called revoking a right. Adding a right is also called granting a right.
If necessary, the administrator can also change a password, delete a user, rename a user.
Who gives a username and password to the database administrator
His user and password is set when installing the DBMS on the database server. He is actually the person who creates the database.