2. Why DBMS - Access Control

The previous page considered flat file spreadsheet database - and very handy they are too. But you soon come up against their limitations when anything slightly complicated is required.

Better access control

In the last example, salary was being introduced to the database. Perhaps the accounts department wanted to store that information on each employee.

But only the accounting staff should see salary - anyone else are only be allowed to see the name-telephone data.

Most DBMS have username/password access controls. This means the system can now identify each user. This in turn means that the 'access privileges' of that person can be determined by the system so that only authorised parts of the system can be viewed / changed.

The technique used to control access is to make a database 'schema' for that person / group - this is explained a bit later.

But the point is that DBMS offers far better security that a simple flat file database.

These are some of the reasons an access control system needs to be in place

• To allow authorised staff to view data in a convenient format for their needs. For instance the sales team want to see sales data in a nicely formatted report, whilst the database support staff might want to see the sales data as a raw table. Same data - different group.
• To restrict access to confidential data
• To protect data integrity and reduce chances of introducing errors. According to who is logged on, they might see an user-friendly form for inputting data along with built-in validation. Whilst another group such as the 'bulk data team' might be able to enter thousands of records in one go via an SQL update query.
• Hide complexity from the user. The data they wish to view might come from dozens of tables or even from other databases altogether. None of this is of interest to the normal user, therefore access rights management selects the appropriate view.