I have a table A in which I need to update a particular field for a list of Products. But the table A has multiple entries of the product. To find out the valid product, I need to check whether that prod is present in table B, if yes, then I have to update one filed of that product. Like this, I have a list of around 3000 products.

Could anyone please help me write the query?

UPDATE AB.ABPD1040 SET CNFIGR_SRC_CD=' '
WHERE PROD_ID IN (SELECT A.PROD_ID
FROM AB.ABPD1040 A,
AB.ABPD1030 B
WHERE A.PROD_ID = B.PROD_ID
AND A.SER_LTR = B.CURR_SER_LTR
AND A.PROD_ID IN ('XXXXX'
,'xxxxxx'..........................);

your query will work... you want us to help in making a simple query.