Mysql #1247-参考'；sid'；不支持（引用组功能）

（参考集团职能部门）--

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如果您需要其他内容，请尝试并还原-

SELECT a.`subject`, GROUP_CONCAT(a.student_id SEPARATOR ',') AS sid, CONCAT( b.fname,' ',b.surname ) AS 'name' 
FROM email AS a 
LEFT JOIN student_registration AS b ON b.student_id=a.student_id 
GROUP BY a.`subject`;

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如果您需要其他内容，请尝试并还原-

SELECT a.`subject`, GROUP_CONCAT(a.student_id SEPARATOR ',') AS sid, CONCAT( b.fname,' ',b.surname ) AS 'name' 
FROM email AS a 
LEFT JOIN student_registration AS b ON b.student_id=a.student_id 
GROUP BY a.`subject`;