Question

我有一个像这样的查询，其中我的子查询正在获取多行。

    SELECT TOOL.ANUM,
       ASSET.ID,
       ASSET.DESCRIPTION,
       TOOL.DATE,
  (SELECT CASE frequnit
              WHEN 'WEEKS' THEN finish+(frequency*7)
              WHEN 'MONTHS' THEN add_months(finish, pfrequency)
              WHEN 'YEARS' THEN add_months(finish, (frequency * 12))
              ELSE actfinish+pluscfrequency
          END AS frequency
   FROM workorder
   WHERE worktype = 'CAL'
     AND pmnum IS NOT NULL
     AND assetnum = '6847'
     AND actfinish <
       (SELECT actfinish
        FROM workorder
        WHERE wonum = '2354850')) freq,
FROM tool,
     Asset
LEFT JOIN PM ON asset.num = pm.num
AND PM.status = 'ACV'
WHERE asset.anum = tool.anum
  AND tool.wo = '2354850'
ORDER BY tool.anum

我的子查询结果是：

SELECT wnum,finish
CASE frequnit
                  WHEN 'WEEKS' THEN finish+(frequency*7)
                  WHEN 'MONTHS' THEN add_months(finish, pfrequency)
                  WHEN 'YEARS' THEN add_months(finish, (frequency * 12))
                  ELSE actfinish+pluscfrequency
              END AS frequency
       FROM workorder
       WHERE worktype = 'CAL'
         AND pmnum IS NOT NULL
         AND assetnum = '6847'
         AND actfinish <
           (SELECT actfinish
            FROM workorder
            WHERE wonum = '2354850')

wnum    finish     frequency
10003   12-NOV-15  13-DEC-2015
10004   14-DEC-15  15-DEC-2015

但我需要子查询中max（finish）的freq值。我可以通过如下使用rownum来获得这个：

select * from (subquery order by finish ) where rownum=1;

但是我不应该使用上面的那个，因为我在引用子查询中的主要查询列之一

assetnum ='6847'（assetnum = TOOL.ANUM）

还有其他办法吗？提前谢谢。

Answer 1

如果你想要最大值，那么使用它呢？

SELECT . . .
       (SELECT MAX(CASE frequnit
                     WHEN 'WEEKS' THEN finish+(frequency*7)
                     WHEN 'MONTHS' THEN add_months(finish, pfrequency)
                     WHEN 'YEARS' THEN add_months(finish, (frequency * 12))
                     ELSE actfinish+pluscfrequency
                   END) AS frequency
        FROM workorder
        WHERE worktype = 'CAL' AND
              pmnum IS NOT NULL AND
              assetnum = '6847' AND
              actfinish < (SELECT actfinish FROM workorder WHERE wonum = '2354850')
       ) freq,
. . .

SQL子查询获取多行

1 个答案: