mysql - mysql COUNT DISTINCT 多列与 WHERE

Question

我正在尝试从单个表中生成数据，该表创建一个报告，显示位置 a、b、c 在上一时期（@dt）发生了多少次。

我可以使单个 SELECT 查询工作，但无法弄清楚如何将它们组合在一起并生成完整的报告。错误是 1241：操作数应该包含 1 列，我已经花了一个小时来处理以前的答案，但完全被卡住了。

SELECT (
SELECT DISTINCT pid, SUM(location like '%a%') FROM db.t WHERE (date > @dt) GROUP BY pid)
 AS 'a', (
SELECT DISTINCT pid, SUM(location like '%b%') FROM db.t WHERE (date > @dt) GROUP BY pid)
 AS 'b', (
SELECT DISTINCT pid, SUM(location like '%c%') FROM db.t WHERE (date > @dt) GROUP BY pid)
 AS 'c';

Answer 1

您在寻找每计数pid吗？如果是这样，这是一个更简单的查询：

 SELECT pid, SUM(location like '%a%') as As,
        SUM(location like '%b%') as Bs,
        SUM(location like '%c%') as Cs
 FROM db.t
 WHERE (date > @dt)
 GROUP BY pid