Mysql SELECT CASE LIKE 给出一个 NULL 行

Posted 2023-02-24

【中文标题】Mysql SELECT CASE LIKE 给出一个 NULL 行

【英文标题】：Mysql SELECT CASE LIKE give a NULL row

【发布时间】：2015-03-01 12:23:43

【问题描述】：

我正在使用以下查询，但它给出了 NULL 行以及其余结果：

SELECT  CASE 
WHEN csuseragent LIKE '%MSIE+8.0%' or csuseragent like '%Trident%' THEN 'IE'
WHEN csuseragent LIKE '%Firefox%' THEN 'Firefox'
WHEN csuseragent LIKE '%chrome%' THEN 'chrome'
END AS Browser ,count(*) as num
FROM logs.log
group by Browser
order by num desc

+---------+--------+
| Browser | num    |
+---------+--------+
| chrome  | 319607 |
| NULL    | 125974 |
| Firefox | 124627 |
| IE      |  56913 |
+---------+--------+

那么如何删除NULL 和125974？

【参考方案1】：

您可以使用having 子句过滤掉组：

SELECT  CASE 
WHEN csuseragent LIKE '%MSIE+8.0%' or csuseragent like '%Trident%' THEN 'IE'
WHEN csuseragent LIKE '%Firefox%' THEN 'Firefox'
WHEN csuseragent LIKE '%chrome%' THEN 'chrome'
END AS Browser ,count(*) as num
FROM logs.log
GROUP BY Browser
HAVING Browser IS NOT NULL
ORDER BY num DESC

【参考方案2】：

给你

SELECT  CASE 
WHEN csuseragent LIKE '%MSIE+8.0%' or csuseragent like '%Trident%' THEN 'IE'
WHEN csuseragent LIKE '%Firefox%' THEN 'Firefox'
WHEN csuseragent LIKE '%chrome%' THEN 'chrome'
WHEN Browser IS NOT NULL
END AS Browser ,count(*) as num
FROM logs.log

group by Browser
order by num desc

【参考方案3】：

添加WHERE Browser IS NOT NULL 子句