MySQL数据库有多个计数

Question

这是我的MySQL表的快照：

是否可以编写查询来获得像输出这样的数据透视表...

Answer 1

像

这样的东西

SELECT url_host,
    SUM(CASE WHEN post_id = -1 THEN 1 ELSE 0 END) as post_id_minus1,
    SUM(CASE WHEN post_id = 0 THEN 1 ELSE 0 END) as post_id_0,
    etc...
FROM    YOUR_TABLE
GROUP BY url_host

Answer 2

您可以使用CASE语句来转动您的表格。

SELECT  url_host,
        COUNT(CASE WHEN post_ID = -1 THEN 1 ELSE NULL END) Negative_One,
        COUNT(CASE WHEN post_ID = 0 THEN 1 ELSE NULL END) Zero,
        COUNT(CASE WHEN post_ID > 0 THEN 1 ELSE NULL END) Greater_Zero
FROM tableName
GROUP BY url_host

SQLFiddle Demo