MERGE INTO dms_wl_info a  ----> 目標表 
     USING (  SELECT c.position, SUM (c.store_qt) COUNT
                FROM dms_goods_stock c
                     LEFT JOIN sys_office d ON d.id = C.BELONG_DEPARTMENT  --> 輔助表（包含目標表需要的資料）
               WHERE     c.position IS NOT NULL
                <if test
 
="warehouse != null and warehouse != ''">
                    AND D.PARENT_IDS LIKE '%'||#{warehouse}||'%'            --> 動態修改
                </if>
            GROUP BY c.position) b
        ON (a.wl_id = b.position)  -->  條件
WHEN MATCHED
THEN
   UPDATE SET a.can_save_qt = A.MAX_QT - b.COUNT  --> 修改語句，可以插入insert ，輸出結果 output等

還有一種批量修改   update_select  語句 參看