How can I update multiple rows based on comparison of fields table1 and 2

Question

I create the following SQL to test what I thought was a method to update those records where the fields below match, but what ends up happening is that the update functions works the first time, and then basically updates everything to null. I am not understanding what I am doing wrong. New at this.
UPDATE SLS_HDR B
SET ( B.ORD_DT, B.SHIP_ADD_CD, B.INV_ADD_CD, B.LOB, B.STATUS,
B.ORD_TYPE, B.HDR_ROUTE, B.PRICE_LIST, B.CUST_ORDER, B.REF_A, B.REF_B,
B.ORD_REF, B.ORD_DISC, B.SREP, B.SREP2, B.PLAN_DEL_DT, B.TXTA, B.TXTB,
B.INV_CONTACT, B.SHIP_CONTACT, B.SOLD_CONTACT, B.PAY_CONTACT, B.ORD_AMT,B.UPDATED_DT )
= (SELECT
A.ORD_DT, A.SHIP_ADD_CD, A.INV_ADD_CD, A.LOB, A.STATUS,
A.ORD_TYPE, A.HDR_ROUTE, A.PRICE_LIST, A.CUST_ORDER, A.REF_A, A.REF_B,
A.ORD_REF, A.ORD_DISC, A.SREP, A.SREP2,A.PLAN_DEL_DT, A.TXTA, A.TXTB,
A.INV_CONTACT, A.SHIP_CONTACT, A.SOLD_CONTACT,A.PAY_CONTACT, A.ORD_AMT, SYSDATE
FROM
SLS_HDR_TEMP A
WHERE
A.FIN_COMP = B.FIN_COMP AND
A.LOG_COMP = B.LOG_COMP AND
A.ORD_NO = B.ORD_NO AND
A.TRANS_DT = B.TRANS_DT AND
A.BP_TYPE = B.BP_TYPE AND
A.STATUS <> B.STATUS);
Can anyone advise?
Thank you,
Edited by: 903292 on Dec 19, 2011 1:15 PM

Answer 1

you donot have where clause in your update so un-matched rows will be updated with null values
UPDATE SLS_HDR B
SET ( B.ORD_DT, B.SHIP_ADD_CD, B.INV_ADD_CD, B.LOB, B.STATUS,
B.ORD_TYPE, B.HDR_ROUTE, B.PRICE_LIST, B.CUST_ORDER, B.REF_A, B.REF_B,
B.ORD_REF, B.ORD_DISC, B.SREP, B.SREP2, B.PLAN_DEL_DT, B.TXTA, B.TXTB,
B.INV_CONTACT, B.SHIP_CONTACT, B.SOLD_CONTACT, B.PAY_CONTACT, B.ORD_AMT,B.UPDATED_DT )
= (
          SELECT
          A.ORD_DT, A.SHIP_ADD_CD, A.INV_ADD_CD, A.LOB, A.STATUS,
          A.ORD_TYPE, A.HDR_ROUTE, A.PRICE_LIST, A.CUST_ORDER, A.REF_A, A.REF_B,
          A.ORD_REF, A.ORD_DISC, A.SREP, A.SREP2,A.PLAN_DEL_DT, A.TXTA, A.TXTB,
          A.INV_CONTACT, A.SHIP_CONTACT, A.SOLD_CONTACT,A.PAY_CONTACT, A.ORD_AMT, SYSDATE
          FROM
          SLS_HDR_TEMP A
          WHERE
          A.FIN_COMP = B.FIN_COMP AND
          A.LOG_COMP = B.LOG_COMP AND
          A.ORD_NO = B.ORD_NO AND
          A.TRANS_DT = B.TRANS_DT AND
          A.BP_TYPE = B.BP_TYPE AND
          A.STATUS= B.STATUS
WHERE EXISTS
     select null from SLS_HDR_TEMP A
     WHERE
     A.FIN_COMP = B.FIN_COMP AND
     A.LOG_COMP = B.LOG_COMP AND
     A.ORD_NO = B.ORD_NO AND
     A.TRANS_DT = B.TRANS_DT AND
     A.BP_TYPE = B.BP_TYPE AND
     A.STATUS= B.STATUS
)OR using Merge
Merge into SLS_HDR B
using SLS_HDR_TEMP A
on (A.FIN_COMP = B.FIN_COMP AND
A.LOG_COMP = B.LOG_COMP AND
A.ORD_NO = B.ORD_NO AND
A.TRANS_DT = B.TRANS_DT AND
A.BP_TYPE = B.BP_TYPE AND
A.STATUS= B.STATUS)
when matched then update set (B.ORD_DT, B.SHIP_ADD_CD, B.INV_ADD_CD, B.LOB, B.STATUS,
B.ORD_TYPE, B.HDR_ROUTE, B.PRICE_LIST, B.CUST_ORDER, B.REF_A, B.REF_B,
B.ORD_REF, B.ORD_DISC, B.SREP, B.SREP2, B.PLAN_DEL_DT, B.TXTA, B.TXTB,
B.INV_CONTACT, B.SHIP_CONTACT, B.SOLD_CONTACT, B.PAY_CONTACT, B.ORD_AMT,B.UPDATED_DT ) = (A.ORD_DT, A.SHIP_ADD_CD, A.INV_ADD_CD, A.LOB, A.STATUS,
A.ORD_TYPE, A.HDR_ROUTE, A.PRICE_LIST, A.CUST_ORDER, A.REF_A, A.REF_B,
A.ORD_REF, A.ORD_DISC, A.SREP, A.SREP2,A.PLAN_DEL_DT, A.TXTA, A.TXTB,
A.INV_CONTACT, A.SHIP_CONTACT, A.SOLD_CONTACT,A.PAY_CONTACT, A.ORD_AMT, SYSDATE)HTH...
Thanks