Microsoft Access - Field Properties - Indexed

Indexed

Field properties are where you fine tune the table. The data type provides general

information about the type of data that a field is going to contain and in the properties is

where you define it more exactly.

You use an index to speed up queries, sorting, and grouping operations run against large amounts of data. You can also use indexes to prevent users from entering duplicate values.

The options are:

No : Turns off indexing (default)

Yes (Duplicates OK) : Indexes the field and allows duplicate values. For example, you may 

                                    have duplicate first and last names

Yes (No Duplicates) :  Indexes the field and does not allow duplicate values

If the field name finishes with ID; key; code or num the indexed property is automatically set to Yes (Duplicates OK).  If you do not need to have these fields indexed then the setting has be changed manually.