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Prevent Duplicate Child Records?

Prevent Duplicate Child Records?

(OP)
I have a station ID table connected to another data (species code) table via one to many relationship using the station ID. Users enter species codes for a station using a form. How can I prevent a user from entering duplicate species codes for a particular station ID. In other words its ok to have duplicate species codes in the data table, but not for a particular station ID. Hope this is not confusing. Thanks for any help.

RE: Prevent Duplicate Child Records?

Would "one to one relationship" do the trick?

Have fun.

---- Andy

RE: Prevent Duplicate Child Records?

3 tables.

Station Table
- StationID
- other station data
Species Table
- SpeciesID
- other species data
Station-Species Table
- StationID
- SpeciesID

This allows a species to be recorded at more than one station, but not more than once at each station. The concept is called a relation table, bridge table, and I think there are a few other names.

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The reasonable man adapts himself to the world. The unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. - George Bernard Shaw


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