Question

SELECT c.Category, SUM(c.[Market Value]), SUM([p.Market Value])
FROM Dec AS c, [NOV] as p
GROUP BY c.Category
;

告诉我该类别不是聚合函数的一部分。我只是想看看两个表的每个类别的总和。我不想只显示某些值，所以我应该使用Join？

编辑：

SELECT c.[Category],  SUM(c.[Market Value]), SUM(p.[Market Value])
FROM Dec AS c
INNER JOIN Nov AS p ON c.ID = p.ID
GROUP BY c.category, p.Category
;

这是我用JOIN编写的，它只是运行不间断的查询。我等一下吗？有80,000行数据，但只按一个月按类别进行一次SUM会立即返回，为什么两张表很难？

Answer 1

您需要UNION所有数据：

SELECT Category, [market Value]
FROM DEC
UNION ALL 
SELECT Category, [market Value]
FROM NOV

运行此查询时，您将获得两个月的合并数据。如果您想获得组合数据的总和，只需使用查询：

SELECT Category, SUM([market Value]) as sum_value
FROM (
SELECT Category, [market Value]
FROM DEC
UNION ALL 
SELECT Category, [market Value]
FROM NOV
) as A
GROUP BY Category

现在，这不是你想要的。你想要两列：一列是十一月，一列是十二月。要做到这一点，你需要稍微修改UNION ALL查询：

SELECT Category, [market Value], 'Dec' as type
FROM DEC
UNION ALL 
SELECT Category, [market Value], 'Nov' as type
FROM NOV

最终的查询将是：

SELECT Category, 
SUM(iif(type='Dec', [Market Value], 0)) as Dec_Value, 
SUM(iif(type='Nov', [Market Value], 0)) as Nov_Value
FROM (
SELECT Category, [market Value], 'Dec' as type
FROM DEC
UNION ALL 
SELECT Category, [market Value], 'Nov' as type
FROM NOV
) as A
GROUP BY Category

MS Access SQL中的两个聚合函数？

1 个答案: