mysql - SQL查询以制作列表等

Question

下面是插入了数据的表格。

CREATE TABLE police(event_id VARCHAR(100), search_type VARCHAR(1000),
                    reported_by VARCHAR(100));
INSERT INTO police VALUES ('gng67g6yf', 'person','ceridigion' );
INSERT INTO police VALUES ('bfewbqfjhfb', 'person', 'ceridigion' );
INSERT INTO police VALUES ('ytftdfctg', 'n/a','ceridigion'  );
INSERT INTO police VALUES ('yufvugyu', 'person','pembrokeshire',  );

我想找出的是一个查询，它将列出 reported_by 并包含在这些区域中发生的搜索。像下面这样的东西:

reported_by     Stopped and searched
ceridigion              2
pembrokeshire           1   

Answer 1

SELECT reported_by,
       SUM(CASE WHEN search_type = 'person' THEN 1 ELSE 0 END) AS `Stopped and searched`
FROM police
GROUP BY reported_by

此处演示:

SQLFiddle