Showing a warning message if records share 2 fields

[freddy k]

Hi,

I've tried searching the forum but not quite sure what to look for.

I have a form which displays a table in datasheet view:

Day: (Date)
Shift: (Text)
WorkerID: (Looks up worker from a different table)

Shifts are pre-entered and then workers are assigned to shifts as and when.

I'm trying to get a warning message to appear if a worker is assigned to two shifts sharing the same date. Sometimes this is desirable but othertimes not.

I have tried adding a BeforeUpdate event using if not IsNull(DLookup( etc... )) but not sure of the syntax or what criteria I would need to use.

Any help would be much appreciated.

Fred

 

[freddy k]

Any ideas?