Question

是否可以从同一子查询中进行多项选择？这是一个我想要构建的示例查询，但是无法弄清楚如何执行它（我意识到查询不起作用，我只是写它来传达我正在尝试做的事情）：< / p>

SELECT 
    (SUM(my_column) FROM stats WHERE condition = 404 AND my_id IN (t) as total), 
    (SUM(my_column) FROM stats WHERE condition = 404 AND condition2 <> 404 AND my_id IN (t) as total2), 
    SELECT my_id
    FROM
    (
        SELECT id AS my_id
        FROM stats
        JOIN my_object ON stats.my_id = my_object.id
        WHERE stats.condition = 404 
        AND my_object.created_at >= '2013-08-03 04:00:00.000000' AND my_object.created_at IS NOT NULL
        AND condition2 <> 404 GROUP BY my_id
    ) AS t

我在postgres工作，但更喜欢ANSI SQL解决方案。

结果数据：

id  total total2
1   5     NULL
2   NULL  6
3   6     9
4   1     1235

谢谢！

Answer 1

很难测试，因为你只提供结果数据而不是输入数据，而且你没有在查询中使用别名，所以不可能确定你的模式，但你可以使用这样的东西： / p>

select
    s.my_id,
    sum(s.my_column) as total, 
    sum(case when s.condition2 <> 404 then s.my_column else 0 end) as total2 
from stats as s
    inner join my_object as o on o.id = s.my_id
where
    s.condition = 404 and
    o.created_at >= '2013-08-03 04:00:00' and
    o.created_at is not null
group by s.my_id

Answer 2

您可能需要对相关子查询中别名的位置进行一些更改，但我认为除此之外，您所做的工作应该有效。

我已经重新设计了你的问题：

SELECT * from
    (
    (select SUM(my_column) FROM stats WHERE condition = 404 AND my_id IN (t)) as total, 
    (select SUM(my_column) FROM stats WHERE condition = 404 AND condition2  404 AND my_id IN (t)) as total2, 
    (SELECT my_id
    FROM
    (
        SELECT id 
        FROM stats
        JOIN my_object ON stats.my_id = my_object.id
        WHERE stats.condition = 404 
        AND my_object.created_at >= '2013-08-03 04:00:00.000000' AND my_object.created_at IS NOT NULL
        AND condition2  404 GROUP BY my_id
    ) AS t) as my_id
    ) x

Answer 3

你需要子查询吗？

SELECT 
    ID,
    SUM(my_column),
    SUM(CASE WHEN condition2 <> 404 THEN my_column ELSE 0 END)
FROM stats
JOIN my_object 
    ON stats.my_id = my_object.id
WHERE stats.condition = 404 
AND my_object.created_at >= '2013-08-03 04:00:00.000000' 
AND my_object.created_at IS NOT NULL
GROUP BY ID

Answer 4

这就是我写外部查询的方式：

SELECT 
my_id AS id,
SUM(CASE WHEN condition = 404 AND my_id IN (t) THEN my_column ELSE 0 END) AS total,
THEN my_column ELSE 0 END) AS total,
SUM(CASE WHEN condition = 404 AND condition2 <> 404 AND my_id IN (t) 
THEN my_column ELSE 0 END) AS total2
FROM (
    SELECT my_id, condition, condition2, etc.
    ...
) AS subqry
GROUP BY my_id

内部查询返回您需要的所有列，外部将过滤它。

SQL - 来自同一子查询的多个where子句？

4 个答案: