Know the fields you expect to use to link tables. If you are uncertain - look again at the example data. It must be a numeric field type. If you are using a numerical code it is usually better to use the Alphanumeric field type. Not everyone agrees about this so you may want to use a number anyway.
Counters are very useful for codes.
It is possible to restructure a table if a field turns out to be too small, or too large. Some software does not limit the length of the field. Practical advice Write the names of the fields and the type of data in it before you begin to create the database. Get the list correct before you move on to creating the tables Creating the database If you have not created tables before - it is a good idea to try a small one and enter a small amount of data to get used to the software. You can then manage your hard disk in an orderly way.