Database: Two columns as primary key

[lozina]

I've got a situation here where I need to have a unique constraint which works on two columns but one of the columns might be null... I know it doesnt work this way though, if its part of primary key it must also be not null, right?

so is there any clever workaround for this?

I guess one cheasy thing is to give column B a default of some stupid value for me to indicate it is empty but I hate that kinda hack.

 

[Apathetic]

Would a composite key be appropriate here?

Dave

 

[ivan2]

u can add a unique constrain to them.

 

[LumbergTech]

as ivan said, unique key