Question

what are the ways of preventing duplicate values in a field ms access...pl help i need it by today!!! urgent!!

Answer 1

You can prevent duplicate values in a field by creating a unique index. A unique index is an index that requires that each value of the indexed field is unique.

There are two basic ways that you can create a unique index:

Set the field's Indexed property to Yes (No duplicates)    You can do this by opening the table in Design view. This method is easy and a good choice if you only want to change one field at a time.

Create a data-definition query that creates the unique index    You can do this by using SQL view. This method is not as easy as using Design view, but has an advantage: you can save the data-definition query and use it again later. This is useful if you periodically delete and re-create tables and want to use unique indexes on some of the fields