mysql – 用于创建列表的SQL查询等

下面是插入数据的表格.

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',  );

我想要找到的是一个查询,它将列出reported_by并在这些区域中进行搜索.如下所示：

reported_by     Stopped and searched
ceridigion              2
pembrokeshire           1   

解决方法:

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

在这里演示：

sqlfiddle