为什么错误＃1066 - 不唯一的表/别名：'cat_rapoarte'
问题描述：
I'm working on a student->parent->teacher grading system for the school I work at and while using MySQL I have received this error. Why?
SELECT `cat_materii`.*
FROM `cat_rapoarte`
INNER JOIN `cat_rapoarte` on
`cat_materii`.`m_id`=`cat_rapoarte`.`rap_m_id`
WHERE `cat_rapoarte`.`k_id` = '7fbXe1dvltedEkIXELc8Q1NeMkKRb3pi' AND (data BETWEEN '2015-11-01' AND '2015-11-30') GROUP BY `rap_m_id`
答
You had the same table twice in the join clause. See the commented part in the query.
SELECT `cat_materii`.*
FROM `cat_materii` --`cat_rapoarte`
INNER JOIN `cat_rapoarte` on `cat_materii`.`m_id`=`cat_rapoarte`.`rap_m_id`
WHERE `cat_rapoarte`.`k_id` = '7fbXe1dvltedEkIXELc8Q1NeMkKRb3pi'
AND (data BETWEEN '2015-11-01' AND '2015-11-30')
GROUP BY `rap_m_id`