Warning: file_get_contents(/data/phpspider/zhask/data//catemap/8/mysql/67.json): failed to open stream: No such file or directory in /data/phpspider/zhask/libs/function.php on line 167

Warning: Invalid argument supplied for foreach() in /data/phpspider/zhask/libs/tag.function.php on line 1116

Notice: Undefined index: in /data/phpspider/zhask/libs/function.php on line 180

Warning: array_chunk() expects parameter 1 to be array, null given in /data/phpspider/zhask/libs/function.php on line 181
Mysql 如何根据特定标准进行分组和计数?_Mysql_Sql - Fatal编程技术网

Mysql 如何根据特定标准进行分组和计数?

Mysql 如何根据特定标准进行分组和计数?,mysql,sql,Mysql,Sql,我有一张有汽车和车库的桌子。每辆车只列在一个车库里,但是一个车库可以有很多车。我想知道车库里每种车有多少辆。每辆车在数据库中都有自己的行 这张桌子看起来像这张 +-------+--------+-----+ |carType| garage |id | +-------+--------+-----+ | 1 | 1 | 1 | +-------+--------+-----+ | 1 | 1 | 2 | +-------+--------+--

我有一张有汽车和车库的桌子。每辆车只列在一个车库里,但是一个车库可以有很多车。我想知道车库里每种车有多少辆。每辆车在数据库中都有自己的行

这张桌子看起来像这张

+-------+--------+-----+
|carType| garage |id   |
+-------+--------+-----+
| 1     | 1      | 1   |
+-------+--------+-----+
| 1     | 1      | 2   |
+-------+--------+-----+
| 1     | 2      | 3   |
+-------+--------+-----+
| 2     | 2      | 4   |
+-------+--------+-----+
这就是我想要的

+-------+------------+--------+
|carType| carCount   | garage |
+-------+------------+--------+
| 1     | 2          | 1      |
+-------+------------+--------+
| 1     | 1          | 2      |
+-------+------------+--------+
| 2     | 1          | 2      |
+-------+------------+--------+
问题是我不知道查询应该是什么样子。

您只需要按carType和garage进行分组:

输出:

carType garage  carCount
1       1       2
1       2       1
2       2       1

我第一次尝试在这里回答一些问题,希望它能成功! 正如Gordon所说,提示分组,如果下面不正确,请大声喊出Gordon

with t
as
(select * from(values(1,1,1),(1,1,2),(1,2,3),(2,2,4)) as t (carType,garage,id))

select carType, count(id) as carCount, garage
from t
group by carType, garage

提示:分组依据。我知道我必须使用分组依据和计数,但如果我按类型分组,它会忽略车库。
with t
as
(select * from(values(1,1,1),(1,1,2),(1,2,3),(2,2,4)) as t (carType,garage,id))

select carType, count(id) as carCount, garage
from t
group by carType, garage