UPDATE dbo.PL_REQUEST_DOC SET PROCESS_ID='APPROVE' WHERE REQ_ID IN (SELECT REQ_ID FROM dbo.PL_REQUEST_DOC WHERE (PROCESS_ID IS NULL OR PROCESS_ID='' )AND EXISTS(SELECT * FROM dbo.PL_REQUEST_PROCESS WHERE PL_REQUEST_DOC.REQ_ID=PL_REQUEST_PROCESS.REQ_ID))