Question

如何在脚本上使用左连接更新表。我正在使用DB2数据库。

我创建了一个select语句，它可以工作：

**

select  t1.estrcd as "transaction code",
        t1.espyno as "payer",
        t1.escuno as "customer no",
        t1.escino as "invoice no",
        t1.esvono as "voucher no",
        t1.escuam as "foreign currency amount",
        COALESCE(t2."received_amount",0) as "received amount",
        t1.escuam + COALESCE(t2."received_amount",0) as "outstanding amount"
from m3edbedu.fsledg t1 left join
        (select espyno, escino, sum(escuam) as "received_amount" from m3edbedu.fsledg
                where estrcd = 20 group by espyno, escino) as t2 on
        t2.espyno = t1.espyno and t2.escino = t1.escino
where t1.esreco = 0 and t1.estrcd = 10 and (t1.escuam + COALESCE(t2."received_amount",0)) = 0
order by t1.espyno, t1.escino, t1.estrcd;

**

但现在他们要求我更新表并将t1.esreco设置为9.我尝试使用以下脚本进行更新，但是我收到了错误。

update m3edbedu.fsledg t1 LEFT JOIN(select espyno, escino, sum(escuam) as "received_amount"
           from m3edbedu.fsledg
           where estrcd = 20
           group by espyno, escino) as t2
           on t2.espyno = t1.espyno and t2.escino = t1.escino set t1.esreco = 9 where t1.esreco = 0 and t1.estrcd = 10 and (t1.escuam + COALESCE(t2."received_amount",0)) = 0 order by t1.espyno, t1.escino, t1.estrcd;1;

错误：SQL0199 - 不期望关键字LEFT。有效令牌：SET。（状态：37000，本机代码：FFFFFF39）错误：SQL0104 - 令牌1不是有效。有效令牌：（CL END GET SET CALL DROP FREE HOLD LOCK OPEN 随着开始。（州：37000，土着法典：FFFFFF98）

我希望有人可以帮助我。

提前致谢。：）

Answer 1

由于这是DB2数据库，因此无法在update语句中指定FROM子句。更新了答案以反映您必须做的事情（请记住，这绝不是优化的）。

update 
    m3edbedu.fsledg t1
set 
    t1.esreco = 9 
where
    t1.esreco = 0 and t1.estrcd = 10 and
    exists(select t2.espyno
        from m3edbedu.fsledg t2
        where t2.estrcd = 20 and t2.espyno = t1.espyno and t2.escino = t1.escino)
    and (t1.escuam + coalesce(
        (select sum(t2.escuam) 
        from m3edbedu.fsledg t2 
        where t2.estrcd = 20 and t2.espyno = t1.espyno and t2.escino = t1.escino), 0) = 0)

Answer 2

DB2不支持UPDATE语句中的连接，因此您必须执行一种解决方法，例如将连接部分作为相关子查询，如下所示：

UPDATE m3edbedu.fsledg update
SET esreco = 9
WHERE EXISTS (
    SELECT 1
    FROM m3edbedu.fsledg t1
    LEFT JOIN(
        SELECT espyno,
               escino,
               sum(escuam) as received_amount
          FROM m3edbedu.fsledg
         WHERE estrcd = 20
         GROUP BY espyno, escino
    ) as t2
    ON t2.espyno = t1.espyno
    AND t2.escino = t1.escino
    WHERE t1.unique_key1 = update.unique_key1
      AND t1.unique_key2 = update.unique_key2
      AND t1.unique_key3 = update.unique_key3
      --etc

      AND t1.esreco = 0
      AND t1.estrcd = 10
      AND (t1.escuam + COALESCE(t2.received_amount,0)) = 0
)

您可能希望通过将UPDATE部分更改为SELECT来检查并确保从子查询中获取正确的列。

Answer 3

请改为尝试：

update t1 
SET t1.esreco = 9
from m3edbedu.fsledg t1 
LEFT JOIN ( select espyno, escino, sum(escuam) as "received_amount" 
            from m3edbedu.fsledg
            where estrcd = 20
            group by espyno, escino) as t2
on t2.espyno = t1.espyno 
and t2.escino = t1.escino 
where t1.esreco = 0 
and t1.estrcd = 10 
and (t1.escuam + COALESCE(t2."received_amount",0)) = 0 ;

使用Left Join更新表

3 个答案: