The following examples are based on a table called 'customer'. It contains the following data:
In this simple data model, each row contains the complete information stored about a particular customer: a number for clear identification, the title to be used in correspondence, the name, the address, and the current account. Other columns needed in real applications have been omitted for the sake of clarity.
From this table, which can become very long and very wide, subtables can be selected for processing purposes or for special tasks. This can be done very easily with the following method: