Using MYSQL GROUP_CONCAT in the WHERE clause

Question

Is it possible to put GROUP_CONCAT in a MYSQL WHERE clause?

I have two tables (one for members and one for payment info). For example

Members Table

num, memNumber, fullName, coporateName, surname
001, mem0010, Joe Bloggs, NULL, Bloggs
002, mem0015, NULL, BBC
003, mem0017, John Peters, NULL
004, mem0101, Emma Jane, NULL

Payment Table

num, memberID, subscriptionYear, amount
001, mem0010, 2008, 30
003, mem0010, 2010, 40
004, mem0015, 2010, 40
005, mem0017, 2009, 35
006, mem0101, 2009, 35
007, mem0017, 2010, 40

I have the following query to retrieve info from both tables (I have simplified it to make it more readable).

SELECT members.num, members.memNumber , members.fullName , members.corporateName ,
       CONCAT(members.corporateName , members.surname) AS searchSurname ,
       GROUP_CONCAT(payment.subscriptionYear) As subscriptionYear ,
       GROUP_CONCAT(payment.amount) AS amount    
FROM members 
LEFT JOIN payment ON members.memNumber = payment.memberID    
WHERE `subscriptionYear` NOT LIKE '%2009%'    
GROUP BY members.num    
ORDER BY `searchSurname` ASC

But it removes the "2009" from the results of the subscriptionYear column. Can't see if 2009 is in the resultant GROUP_CONCAT?

Answer 1

在分组之前，您希望使用HAVING，这在分组后发生。

Answer 2

The clause "HAVING" is used when it is necessary to use a filter after a group (GROUP BY, GROUP_COCANT, ...). Instead, the "WHERE" clause creates a filter before the agroupment happens.

You could use the code bellow:

SELECT members.num, members.memNumber , members.fullName , members.corporateName ,
       CONCAT(members.corporateName , members.surname) AS searchSurname ,
       GROUP_CONCAT(payment.subscriptionYear) As subscriptionYear ,
       GROUP_CONCAT(payment.amount) AS amount    
FROM members 
LEFT JOIN payment ON members.memNumber = payment.memberID    
HAVING `subscriptionYear` NOT LIKE '%2009%'    
GROUP BY members.num    
ORDER BY `searchSurname` ASC

In case, on MYSQL it is not possible to mention a GROUP_CONCAT or a alias on WHERE clause, because WHERE clause happens before it. The HAVING clause also fix this issue.