MySQL - Using COUNT(*) in the WHERE clause

问题

I am trying to accomplish the following in MySQL (see pseudo code)

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

Is there a way to do this without using a (SELECT...) in the WHERE clause because that would seem like a waste of resources.

回答1:

try this;

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

回答2:

I'm not sure about what you're trying to do... maybe something like

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

回答3:

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

EDIT (if you just want the gids):

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

回答4:

try

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

回答5:

Just academic version without having clause:

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

回答6:

There can't be aggregate functions (Ex. COUNT, MAX, etc.) in A WHERE clause. Hence we use the HAVING clause instead. Therefore the whole query would be similar to this:

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;

回答7:

-- searching for weather stations with missing half-hourly records

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;

-- variation of yapiskan with a where .. in .. select

回答8:

i think you can not add count() with where. now see why ....

where is not same as having , having means you are working or dealing with group and same work of count , it is also dealing with the whole group ,

now how count it is working as whole group

create a table and enter some id's and then use:

select count(*) from table_name

you will find the total values means it is indicating some group ! so where does added with count() ;

回答9:

COUNT(*) can only be used with HAVING and must be used after GROUP BY statement Please find the following example:

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

来源：https://stackoverflow.com/questions/301793/mysql-using-count-in-the-where-clause

标签

mysql

count

aggregation

having