i am using Like in group concat & i want to get all modules attached to client even if it does not match to LIKE, i know that that i can do that with HAVING but i don’t want to use HAVING, any solution with WHERE or in join condition ?
Any suggestions on how to get my expected result??
These are some basic tables and the query i tried along with results i get and the result i really wanted
Tables
Client +--------------------+ | id | name | +--------------------+ | 1 | client1 | | 2 | client2 | | 3 | client3 | | 4 | client4 | +--------------------+ Module +--------------------+ | id | name | +--------------------+ | 1 | module1 | | 2 | module2 | | 3 | module3 | | 4 | module4 | +--------------------+ Client_Module +-------------------------+ | client_id | module_id | +-------------------------+ | 1 | 1 | | 1 | 3 | | 2 | 1 | | 2 | 2 | | 2 | 4 | | 3 | 2 | | 4 | 1 | | 4 | 2 | | 4 | 3 | | 4 | 4 | +-------------------------+
Query:
SELECT client.id, client.name, GROUP_CONCAT(module.name) AS modules FROM client LEFT JOIN client_module ON client_module.client_id = client.id LEFT JOIN module ON module.id = client_module.module.id WHERE module.name LIKE '%module1%' group by client.id
Results:
Received +--------------------------------------------------+ | id | name | modules | +--------------------------------------------------+ | 1 | client1 | module1 | | 2 | client2 | module1 | | 4 | client4 | module1 | +--------------------------------------------------+ Expected +------------------------------------------------------+ | id | name | modules | +------------------------------------------------------+ | 1 | client1 | module1,module3 | | 2 | client2 | module1,module2,module4 | | 4 | client4 | module1,module2,module3,module4 | +------------------------------------------------------+
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Answer
This is possible without HAVING
by using EXISTS
:
SELECT c.id, c.name, GROUP_CONCAT(m.name) AS modules FROM client AS c INNER JOIN client_module AS cm ON cm.client_id = c.id INNER JOIN module AS m ON m.id = cm.module_id WHERE EXISTS ( SELECT 1 FROM client_module AS cm2 INNER JOIN module AS m2 ON m2.id = cm2.module_id WHERE m2.name LIKE '%module1%' AND cm2.client_id = c.id ) GROUP BY c.id, c.name;
But this is less efficient, and more verbose so offers no advantage whatsoever. I expect your reasons for using HAVING
are largely unfounded, and the approach I would personally take is with a conditional count in the HAVING
clause:
SELECT c.id, c.name, GROUP_CONCAT(m.name) AS modules FROM client AS c INNER JOIN client_module AS cm ON cm.client_id = c.id INNER JOIN module AS m ON m.id = cm.module_id GROUP BY c.id, c.name HAVING COUNT(CASE WHEN m.name LIKE '%module1%' THEN 1 END) > 0;