SqlDataAdapter.Fill(DataSet)

[liquid_]

I'm going to bind data set to combo boxes. Data set is compound from 2 tables and joined by relation. The declaration is as follows: Private tablePRAgent As PRAgentDataTable Private tablePRAgentLocation As PRAgentLocationDataTable Private relationPRAgentPRAgentLocation As DataRelation The table PRAgentDataTable has main rows with details in table PRAgentLocationDataTable. So first combo is bound to PRAgentDataTable and second - to PRAgentLocationDataTable, by relation. Filling adapters (and in consequence combos) while I add clause "WHERE col=@parameter" ends with "exception of type 'System.Data.ConstraintException'". When there is no WHERE clause everything goes right. How could I overcome this problem?