Prevent Duplicate Values in Access database

[Jim P]

How do I set the non-primary index which uses multiple fields so that I
cannot enter duplicate values in the multi-field index? I have tried
defining the multiple field index and then clicking YES on Uniqueness, but
this does not prevent duplicate entries in the table.

 

[Duane Hookom]

Creating a unique index on one or more fields should always insure
uniqueness. Are you for sure allowed to save table?

 

[Jeff Boyce]

Are your warnings turned off? This might dovetail with Duane's response,
not letting you see that your changes weren't saved. Can you confirm that
the index is still set after closing the table design window and re-opening
it?

Regards

Jeff Boyce
<Access MVP>