Non Duplicated Data

[puforee]

In a table or on a form how do I keep from having duplicate data. I do not want to use the primary key because the data is not required for all records and primary key fields cannot be blank. But...when it is required I do not want it to be duplicated in any other record. This data would be serial numbers. I have 10 different ones and cannot duplicate their use.

Thanks,

 

[Remou]

A unique index can be null.

 

[puforee]

Remou,

Ahhhhhh thank you very much. :-D