>SELECT Billing_charges.*, Viscodes.ccode_description; > FROM ; > Billing_charges ; > LEFT OUTER JOIN VisCodes ; > ON Viscodes.ccode_value LIKE ( Billing_charges.crevenue_code+"%" ); > AND Viscodes.ccategory_description LIKE ( "REVENUE_CODES%" ) > WHERE Billing_charges.cbilling_main_fk = ( ?vp_cBilling_main_fk ) >These two queries are supposed to be the same. Can you explain the difference between these two? It looks like yours works every time, while the original with IsNull sometimes fails to work. I can not understand it.