What is the type of the @EqupmentId variable? If it's integer, then you may want

if COALESCE(@EquipmentId, 0) !=0 -- this tests for value being not null and not 0



>>Why does it have to be one line?
>>

>>if COALESCE(@EquipmentId,'') !=''
>>   begin
>>   select @Pk = equip_pk from dbo.eq_file where Id_Number = @EquipmentId;
>>   if @Pk==null
>>             begin
>>                 raieserror ...
>>                 return 
>>             end
>>     end

>
>I don't know how COALESCE() works but in my test, when I pass a value to @EquipmentId, the code never goes to SELECT ..