Question

我正在尝试在MySQL中完成以下操作（请参阅pseudo代码）

SELECT DISTINCT gid
FROM `gd`
WHERE COUNT(*) > 10
ORDER BY lastupdated DESC

有没有办法在WHERE子句中不使用（SELECT ...）来执行此操作，因为这似乎是浪费资源。

Answer 1

试试这个;

select gid
from `gd`
group by gid 
having count(*) > 10
order by lastupdated desc

Answer 2

我不确定你要做什么...也许像是

SELECT gid, COUNT(*) AS num FROM gd GROUP BY gid HAVING num > 10 ORDER BY lastupdated DESC

Answer 3

SELECT COUNT(*)
FROM `gd`
GROUP BY gid
HAVING COUNT(gid) > 10
ORDER BY lastupdated DESC;

编辑（如果你只想要gids）：

SELECT MIN(gid)
FROM `gd`
GROUP BY gid
HAVING COUNT(gid) > 10
ORDER BY lastupdated DESC

Answer 4

试

SELECT DISTINCT gid
FROM `gd`
group by gid
having count(*) > 10
ORDER BY max(lastupdated) DESC

Answer 5

没有条款的学术版：

select *
from (
   select gid, count(*) as tmpcount from gd group by gid
) as tmp
where tmpcount > 10;

Answer 6

A WHERE子句中不能有聚合函数（例如COUNT，MAX等）。因此我们改用HAVING子句。因此整个查询将类似于：

SELECT column_name, aggregate_function(column_name)
FROM table_name
WHERE column_name operator value
GROUP BY column_name
HAVING aggregate_function(column_name) operator value;

Answer 7

- 搜索缺少半小时记录的气象站

SELECT stationid
FROM weather_data 
WHERE  `Timestamp` LIKE '2011-11-15 %'  AND 
stationid IN (SELECT `ID` FROM `weather_stations`)
GROUP BY stationid 
HAVING COUNT(*) != 48;

- yapiskan的变体与where .. in .. select

Answer 8

我认为您无法使用count()添加where。现在明白为什么......

where与having不同，having表示您正在工作或处理群体和同样的计数工作，它也在处理整个群体，

现在如何统计它是整个群体的工作

创建一个表并输入一些id然后使用：

select count(*) from table_name

你会发现总值意味着它表示某个群体！所以where添加了count();

Answer 9

COUNT（*）仅可与HAVING一起使用，并且必须在GROUP BY之后使用声明请找到以下示例：

SELECT COUNT(*), M_Director.PID FROM Movie
INNER JOIN M_Director ON Movie.MID = M_Director.MID 
GROUP BY M_Director.PID
HAVING COUNT(*) > 10
ORDER BY COUNT(*) ASC

MySQL - 在WHERE子句中使用COUNT（*）

9 个答案: