What can a Relational Database do?
The DBMS allows us to run a query. This query has selected customers who have not paid their accounts by 11/12/02. This gives a readout like this: These are the customers whose accounts are overdue. The select query is quite a simple query to set up. There are other kinds of query that we can use: Action queries these do something to the data. There are four kinds: Delete query that deletes records according to a criterion, for example all businesses in postcode TS1. Append query that adds records to a table. A Make Table which selects records with fields of choice and allows the table to be exported to another database, or a back up table to be made. For example employee records can be selected from the finance departments database and exported to the personnel department. Archive tables can be made this way as well. Update queries can be used to make a global change, for example a price rise of 5 %. • Parameter queries allow you to select data between certain values, and produces a t
