使用 group by 子句的 MySQL 查询返回的行数比不使用 group by 子句时返回的行数多
没有group by子句，只返回1条记录；其中，返回所需的记录数
SELECT
PM.id AS id, PM.email AS email, PM.name AS name, PM.mobile AS mobile,
PM.country AS country, PM.status AS status, PM.cdate AS joined_date,
PM.details_status AS details_status, PM.freeze AS freeze, PM.blacklist AS blacklist,
PM.blacklist_remark AS blacklist_remark, PM.blacklist_adate AS blacklist_adate,
MA.m_app_id AS app_id, MA.full_name AS replace_name, MAX(MA.ldate) AS ldate,
MA.service_type AS svc_type
FROM whatever_db.tw_person_merchant PM
LEFT JOIN (
whatever_db.tw_person_merchant PMM
INNER JOIN
whatever_db.tw_merchant_application_details MA
ON PMM.app_id = MA.m_app_id
INNER JOIN
whatever_db.tw_merchant_application MAP
ON MA.m_app_id = MAP.id
AND MAP.status NOT IN ('10' , '60')
AND MA.id = (SELECT max(id) FROM whatever_db.tw_merchant_application_details WHERE m_app_id = PMM.app_id )
) ON PM.app_id = MA.m_app_id
WHERE PM.details_status IN ('90', '0')
AND PM.blacklist = 0
AND PM.name != ''
-- **here, without the group by clause, the result is just 1 record
GROUP BY PM.id
ORDER BY PM.id DESC
我正在测试sql脚本是否有相关商家返回，但中间只显示1条记录，经过反复试验，插入的“group by”解决了这个问题。但这个“group by”不是总结，而是显示比没有它更多的结果。意想不到的结果和如此背叛理智的行为。
