我需要一个查询，该查询将获取具有4种不同条件的sum（column），其中条件按条件分组

Question

这是我的查询：

SELECT
    date,
    (SELECT sum(sessions) as org FROM datatwo WHERE medium='Organic Search' GROUP by date),
    (SELECT sum(sessions) as soc FROM datatwo WHERE medium='Social' GROUP BY date),
    (SELECT sum(sessions) as dir FROM datatwo WHERE medium='Direct' group by date),
    (SELECT sum(sessions) as ref FROM datatwo WHERE medium='Referral')
FROM datatwo
GROUP BY date

我试图在一个查询中组合4个查询，但出现此错误，我正在使用mysql DB。

1242-子查询返回多于1行

Answer 1

当您将查询结果用作列时，它必须恰好返回一行和一列。 像这样的表达式：

(SELECT sum(sessions) as org FROM datatwo WHERE medium='Organic Search' GROUP by date)

将为每个不同的date值返回一行。

我怀疑你想要这个：

SELECT
    date,
    sum(case when medium='Organic Search' then sessions end) as org,
    sum(case when medium='Social' then sessions end) as soc,
    sum(case when medium='Direct' then sessions end) as dir,
    sum(case when medium='Referral' then sessions end) as ref
FROM datatwo
GROUP BY date