我有2个与多对多关系相关的实体
客户,服务,clients_has_services。
我需要使用其各自的客户数量来检索所有服务,如下所示:
服务1 20
服务2 10
服务3 5服务
4 0
....
我在进行该查询时遇到问题,该查询仅返回一条记录:
SELECT
services.id as id,
services.name as name,
COUNT(clients_has_services.services_id) as ranking
FROM services
LEFT JOIN clients_has_services ON services.id = clients_has_services.services_id
您需要一个group by子句:
SELECT
services.id as id,
services.name as name,
COUNT(clients_has_services.services_id) as ranking
FROM services
LEFT JOIN clients_has_services ON services.id = clients_has_services.services_id
GROUP BY
services.id,
services.name
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我来说两句