oracle update join

今天需要写一个根据关联查询结果更新数据的sql,mysql中支持这样的语法:

mysql:

UPDATE T1, T2,
[INNER JOIN | LEFT JOIN] T1 ON T1.C1 = T2. C1
SET T1.C2 = T2.C2, 
    T2.C3 = expr
WHERE condition

但是oracle不支持上面的语法,oracle实现上面功能的语法结构如下:

oracle 方式1:

UPDATE table1 
  SET table1.value = (SELECT table2.CODE 
                      FROM table2 
                      WHERE table1.value = table2.DESC)
WHERE table1.UPDATETYPE=‘blah‘
AND EXISTS (SELECT table2.CODE
            FROM table2 
            WHERE table1.value = table2.DESC);

或者

oracle 方式2:

UPDATE 
(SELECT table1.value as OLD, table2.CODE as NEW
 FROM table1
 INNER JOIN table2
 ON table1.value = table2.DESC
 WHERE table1.UPDATETYPE=‘blah‘
) t
SET t.OLD = t.NEW

oracle update join

原文：https://www.cnblogs.com/chengmuyu/p/15138901.html