Fix unsafe query
Fix unsafe query

Uniqueness of this compound index was not guaranteed.
Many thanks to srault95 for this one.

MichelJuillard/dlstats,mmalter/dlstats,mmalter/dlstats,MichelJuillard/dlstats,Widukind/dlstats,MichelJuillard/dlstats,mmalter/dlstats,Widukind/dlstats