====== Update Join ======
==== Oracle ====
<code sql>
-- 1. SubQuery 를 이용한 Update
UPDATE emp e
   SET e.dname = (SELECT d.dname FROM dept d WHERE d.deptno = e.deptno)
 WHERE EXISTS (SELECT 0 FROM dept d WHERE d.deptno = e.deptno)
;
-- 2. Updatable Join View 이용
--    단, d.deptno 가 반드시 PK 이어야 함
--    10G 까지는 PK 아니더라도 힌트로 제어 가능(/*+ bypass_ujvc */)
UPDATE /*+ bypass_ujvc */
       (SELECT e.dname
             , d.dname AS dname_new
          FROM emp  e
             , dept d
         WHERE d.deptno = e.deptno
        )
   SET dname = dname_new
;
-- 3. Merge
MERGE INTO emp e
USING dept d
ON (d.deptno = e.deptno)
WHEN MATCHED THEN
UPDATE SET e.dname = d.dname
;
</code>
==== SQL Server ====
<code sql>
-- From 절 사용 조인 --
UPDATE e
   SET e.dname = d.dname
  FROM emp e
 INNER JOIN dept d
    ON d.deptno = e.deptno
</code>
=== Sample ===
<code sql>
update b
set B.QUERY_PARAM_NAME = substring(b.QUERY_PARAM_NAME,4,80)
from FRM_QUERY_DEF_PARAM b
join FRM_QUERY_DEF A
ON A.QUERY_DEF_ID = B.QUERY_DEF_ID
AND A.QUERY_NAME like 'PAY%'
where QUERY_PARAM_NAME in ('av_ret_code','av_ret_message')
and QUERY_PARAM_INOUT_TYPE = 'out'
</code>
==== MySQL ====
<code sql>
-- Update 절에서 바로 조인 --
-- SET sql_safe_updates = 0;
UPDATE emp e
 INNER JOIN dept d
    ON d.deptno = e.deptno
   SET e.dname = d.dname
;
</code>