子查询中的MySQL COUNT行

Question

I've got this MySQL statement that returns a list of all of our dealers, along with total amount of stores they have. I'm trying to make it so that I can add additional columns that are returned depending on the stores joineddate column.

This is the basic statement that returns the list of dealers (accountgroup) and the total / COUNT of stores that are assigned to accountgroup.

SELECT accountgroup, COUNT(storename) AS TotalAmountOfStores 
FROM accounts 
WHERE accountgroup <>'' 
AND othercode ='Site' 
GROUP BY accountgroup 

I thought using the below statement in a SELECT subquery would let me have these additional columns that I want. This statement works on it's own, but I haven't been able to encorporate it into the above statement as a subquery successfully.

SELECT COUNT( storename ) AS  '2months'
FROM  `accounts` 
WHERE joineddate > date_sub(now(), interval 2 month)
AND accountgroup <>  ''
AND othercode =  'Site'
GROUP BY accountgroup

This is the statement that I thought would work, but I get the error "#1242 - Subquery returns more than 1 row, which confuses me as it should be returning more than one row":

SELECT accountgroup, COUNT(storename) AS TotalAmountOfStores, 
(SELECT COUNT(storename)
FROM `accounts`
WHERE joineddate > date_sub(now(), interval 2 month) AND accountgroup <>'' AND othercode='Site'
GROUP BY accountgroup ) AS '2months' 
FROM accounts 
WHERE accountgroup <>'' 
AND othercode ='Site' 
GROUP BY accountgroup 

I'm starting to feel that a subquery isn't the right approach, and am reading up on JOIN' s. Can anybody confirm this, and possibly point me in the right direction?

Any help is greatly appreciated. Thanks in advance.

Answer 1

You can SUM the times this condition is true using an if. Example:

SELECT 
accountgroup, 
COUNT(storename) AS TotalAmountOfStores, 
SUM(
    IF(joineddate > date_sub(now(), interval 2 month), 1, 0) 
) AS '2months'
FROM accounts 
WHERE accountgroup <>'' 
AND othercode ='Site' 
GROUP BY accountgroup