根据同一表中其他行的值更新行

Question

files_imported
--------
ID (PK)
SPN
FILE_ID
LISTPRICE
ACTION

I need to search and UPDATE TableA and SET ACTION='A' WHERE the value of PRICE in a row with a given SPN is not equal to the value of PRICE found for a different FILE_ID and matching SPN.

I can do it with PHP by breaking the task into smaller queries but i'd rather have a clean solution with MySQL.

This is how far I've gotten:

UPDATE files_imported fi1
JOIN files_imported fi2
    ON fi1.SPN = fi2.SPN
SET ACTION = 'M' 
WHERE fi1.file_id = 980987987
AND fi1.listprice <> fi2.listprice

Answer 1

UPDATE files_imported fi1, files_imported fi2
SET f11.ACTION = 'M' 
WHERE fi1.file_id = 980987987
AND fi1.SPN = fi2.SPN /* same SPN*/
AND fi1.listprice <> fi2.listprice /* different price */
AND fi1.file_id <> fi2.file_id /* different file */