Enforce Constraints on Data Table. Failed to enable constraints. One or more rows contain values.

Actually agree with Daniel, normally you just do something like this: 

Dim dt As DataTable = Nothing
Using dbConnApp As DbConnInfo = BRAPi.Database.CreateApplicationDbConnInfo(si)
dt = BRApi.Database.ExecuteSql(dbConnApp, sql.ToString, False)
End Using

Or this: 

Using dt As DataTable = BRApi.Database.ExecuteSql(dbConnApp, sql.ToString, False)

End Using