Preventing dupicate combinations of fields

[StephenB]

Is it possible to prevent the same combination of entries for a group of field as in other records?

For example; I have a db with four fields (record number, A, B, and C). The entries for record #1 are [A]: Blue, : Green and [C]: Red. Record # 2 allows [A]: Blue, : Blue and [C]: Red and record #3 allows [A]: Red, : Red and [C]: Red, but [A]: Blue, : Green and [C]: Red is never again allowed because it has been used already.

Any thoughts?

 

[Alexandre]

You need to create a multiple-fields unique index. In table design view, click on the Indexes toolbar button, enter a name for the index in the first column of the first blank line
Select the first field to include in the multiple index, in the second column of the same line. In the 2nd line, 2nd column select the second field, etc.