Query slows the system.

Question

There is one query which is giving some problem in the production site:
SELECT ID, REGISTERED_USER_ID, BILL_TO_FIRST_NAME,ADDRESS,ORDER_STATUS,ORDER_SUBMISSION_DATE FROM ORDERS WHERE REGISTERED_USER_ID =@PO AND
ORDER_STATUS='COMPLETE' AND
ID IN( SELECT ORDER_ID FROM PACKAGE_HEADER WHERE PACKAGE_HEADER.ORDER_ID= ORDERS.ID)
ORDER BY ORDER_SUBMISSION_DATE DESC
I want to optimism this query. I guess using joins concept we can optimise it further.
Can any one please advice me on this.
Thanks.

Answer 1

Check if this okay for you.
SELECT A.ID,
       A.REGISTERED_USER_ID,
       A.BILL_TO_FIRST_NAME,
       A.ADDRESS,
       A.ORDER_STATUS,
       A.ORDER_SUBMISSION_DATE
FROM ORDERS A
    ,PACKAGE_HEADER B
WHERE A.REGISTERED_USER_ID = @PO
AND A.ORDER_STATUS = 'COMPLETE'
AND A.ID = B.ORDER_ID
ORDER BY ORDER_SUBMISSION_DATE DESCCheers
Sarma.