MySQL：Sum() 和 Count 在一个查询中？

Question

I'm looking for help using sum() and count () in my SQL query:

select s1_s2,count(s1_s2) as RES 
from city_user 
where s1_s2 in (select s1_s2 from city_user ) 
group by s1_s2

result: Image Query Result

I want to make sum () for RES column

Is that possible?

Answer 1

To select the count of individual s1_s2 values the following query may help

select s1_s2, count(s1_s2) as res 
from city_user 
group by s1_s2;

To obtain the sum of res column the following query may help

select sum(res) as sum 
from 
    (select s1_s2, count(s1_s2) as res 
     from city_user 
     group by s1_s1) 
city_user;

which is the same as

select count(s1_s2) as count 
from city_user;

Reason : It's because you are trying to group the column based on s1_s2 and obtain its count and store it as Res column and calculate its sum which is same as the number of rows for s1_s2 in the table.

Answer 2

thanks for your answers

this what I wanted:

look this pic : result

this query works fine for me:

select s1_s2,
count(s1_s2) as res,
(select sum(res) as sum from (
  select s1_s2, count(s1_s2) as res from city_user group by s1_s2) city_user) as Sum_RES from city_user  group by s1_s2

Answer 3

Probably you can use a outer query like below, again your WHERE condition makes no sense as your IN clause takes all values of column s1_s2 from same table which will always be true

select *, SUM(RES) as SUM_RES
FROM (
select s1_s2,
count(s1_s2) as RES 
from city_user 
group by s1_s2) xxx

Answer 4

Your query makes little sense. where s1_s2 in (select s1_s2 from city_user ) is just a complicated and REALLY inefficient way of writing where s1_s2 is not null .

The sum of the RES column is basically the count of all rows in city_user , or at least those rows in city_user for which s1_s2 is not null. For the sake of people that need to read your queries in the future, including yourself, make it two queries:

select s1_s2,count(s1_s2) as RES 
from city_user 
where s1_s2 is not null
group by s1_s2

and

select count(*)
from city_user
where s1_s2 is not null