Question

以下查询返回按总金额排序的最受欢迎的剧院和行类型组合的列表：例如：

NAME      ROWTYPE  TOTALAMOUNT
theatre1  middle   200
theatre2  front    190
theatre1  front    150
theatre2  middle   100

而我所需要的只是每个剧院的最大值：

theatre1  middle   200
theatre2  front    190

查询：

SELECT name, rowtype, sum
from ( select
name, rowtype, sum(totalamount) sum from trow, fact, theatre

Where trow.trowid = fact.trowid
AND
theatre.theatreid = fact.theatreid

GROUP BY rowtype, name
)

ORDER BY sum DESC, name, rowtype ;

Answer 1

将您当前的查询放入公用表格表达式，然后使用窗口函数查找每个影院的最大总金额。

WITH cte AS
(
    SELECT name, rowtype, SUM(totalamount) sum
    FROM trow
    INNER JOIN fact
        ON trow.trowid = fact.trowid
    INNER JOIN theatre
        ON theatre.theatreid = fact.theatreid
    GROUP BY name, rowtype
)

SELECT name, rowtype, sum
FROM
(
    SELECT name,
           rowtype,
           sum,
           MAX(sum) OVER (PARTITION BY name) maxSum
    FROM cte
) t
WHERE t.sum = t.maxSum

Answer 2

您可以使用窗口函数：

select name, rowtype, sum
from (select name, rowtype, sum(totalamount) as sumta,
             max(sum(totalamount)) over (partition by name) as maxsumta
      from trow join
           fact
           on trow.trowid = fact.trowid join
           theatre
           on  theatre.theatreid = fact.theatreid
     group byrowtype, name
    ) nr
where sumta = maxsumta;

此外，您应该学会使用正确的，明确的JOIN语法。一个简单的规则：从不在FROM子句中使用逗号。始终使用正确的显式JOIN语法。

ORACLE - MAX和SUM

2 个答案: