如何識別在加入父別名（選擇

Question

我得到的錯誤如下：

ER_BAD_FIELD_ERROR: Unknown column 'c.id' in 'where clause':

SELECT * 
FROM clients c 
LEFT JOIN 
    (SELECT GROUP_CONCAT(smpp_user), client_id 
    FROM client_accounts 
    WHERE client_id = c.id) AS l ON 
    l.client_id = c.id 

我需要從主SELECT用WHERE組smpp_user列各c.id

請幫助？我相信這是可能的。

Answer 1

只需在您的子查詢中刪除WHERE子句並使用GROUP BY：

SELECT * 
FROM clients c 
LEFT JOIN (
    SELECT GROUP_CONCAT(smpp_user), client_id 
    FROM client_accounts 
    GROUP BY client_id 
) AS l ON l.client_id = c.id