Denis,

SELECT ... and ExecuteNonQuery can not be used together. You must get the query result back to know if it does indeed exist. You might be able to use ExecuteNonQuery if you call a stored proc and retrieve an OUTPUT parameter value.

>I need only check - exist record or not for current condition.. so ExecuteNonQuery - what I need

>>> loCommand = New SqlCommand("SELECT id FROM Clients WHERE (mandator =