sql-server - 如何将结果合并到一条线上

Question

我有一个查询，我正在尝试使用 SQL Server 将其合并到 1 行。它一直迫使我按 Frequency 列分组，但我只想按 UserId 分组。谁能告诉我我做错了什么。

代码:

SELECT userid, frequency,
(select count(frequency) where frequency = 1) AS Onetime,
(select count(frequency) where frequency = 2) AS Daily,
(select count(frequency) where frequency = 3) AS Weekly,
(select count(frequency) where frequency = 4) AS Fortnightly,
(select count(frequency) where frequency = 5) AS Monthly,
(select count(frequency) where frequency = 6) AS Quarterly,
(select count(frequency) where frequency = 7) AS SemiAnnual,
(select count(frequency) where frequency = 8) AS Annual
FROM AppTasks
where userid = 'userid@gmail.com'
group by UserID, Frequency

数据:

Answer 1

你能试试这个吗？

SELECT userid,
SUM(CASE WHEN frequency = 1 THEN 1 ELSE 0 END) AS Onetime,
SUM(CASE WHEN frequency = 2 THEN 1 ELSE 0 END) AS Daily,
SUM(CASE WHEN frequency = 3 THEN 1 ELSE 0 END) AS Weekly,
SUM(CASE WHEN frequency = 4 THEN 1 ELSE 0 END) AS Fortnightly,
SUM(CASE WHEN frequency = 5 THEN 1 ELSE 0 END) AS Monthly,
SUM(CASE WHEN frequency = 6 THEN 1 ELSE 0 END) AS Quarterly,
SUM(CASE WHEN frequency = 7 THEN 1 ELSE 0 END) AS SemiAnnual,
FROM AppTasks
where userid = 'userid@gmail.com'
group by UserID;