oracle update更新的问题

Question

 update customerbak1  set owner=(select handleby_id 
 from tx where tx.customer_guid=customerbak1.customer_guid )
这个sql更新 受影响行数有365503行而卧用   
 select count(*) from customerbak1 where customer_guid in(select customer_guid from tx)
查出记录数为5586，而 select count(*) from customerbak1 出来的记录正好是365503行 ，请问为何我这条update有问题？
正常应该更新的记录数应该是5586行啊？
求高手解答

Answer 1

update customerbak1 set owner=(select handleby_id  
 from tx where tx.customer_guid=customerbak1.customer_guid )
where customer_guid in(select customer_guid from tx)

Answer 2

可以把in改成exists试一下。或者
UPDATE customerbak1 aa
   SET owner =
        (SELECT handleby_id
           FROM tx
          WHERE tx.customer_guid = aa.customer_guid
            AND EXISTS
          (SELECT 1 FROM TX WHERE tx.customer_guid = aa.customer_guid));

Answer 3

update customerbak1 set owner=(select handleby_id  
 from tx where tx.customer_guid=customerbak1.customer_guid )
少了where 条件.
update customerbak1 set owner=(select handleby_id  
 from tx where tx.customer_guid=customerbak1.customer_guid ) where x