update a set a.ye=(select b.ye from a, b where b.xmdh=a.xmdh)
MERGE INTO DM_DELIVERYLIST_DETAILS DE
USING DM_DELIVERYLIST DM ON (DM.ORDER_NO=DE.ORDER_NO)
WHEN MATCHED THEN UPDATE SET DE.TASK_NO=DM.TASK_NO;
注意meger on 后面必须有括号；
方法一：
UPDATE DM_DELIVERYLIST DM
set DM.ORDER_NO=(SELECT T.order_no
FROM
(SELECT row_id,order_no
FROM (SELECT order_no ,ROWNUM nums FROM (SELECT DISTINCT order_no FROM DM_DELIVERYLIST_DETAILS) ) a
LEFT JOIN (SELECT row_id,ROWNUM nums FROM DM_DELIVERYLIST dm) b ON a.nums=b.nums) T
WHERE T.ROW_ID=DM.ROW_ID
)
WHERE EXISTS(SELECT 1 FROM
(SELECT order_no ,ROWNUM nums FROM (SELECT DISTINCT order_no FROM DM_DELIVERYLIST_DETAILS) ) a
LEFT JOIN (SELECT row_id,ROWNUM nums FROM DM_DELIVERYLIST dm) b ON a.nums=b.nums) T
WHERE T.ROW_ID=DM.ROW_ID
)
;
增where条件提高速度；
方法二：
MERGE INTO DM_DELIVERYLIST Dm
USING (SELECT row_id,order_no
FROM (SELECT order_no ,ROWNUM nums FROM (SELECT DISTINCT order_no FROM DM_DELIVERYLIST_DETAILS) ) a
LEFT JOIN (SELECT row_id,ROWNUM nums FROM DM_DELIVERYLIST dm) b ON a.nums=b.nums) T
ON (T.ROW_ID=DM.ROW_ID)
WHEN MATCHED THEN UPDATE SET DM.ORDER_NO=T.ORDER_NO;