需要更正mysql查询

Question

UPDATE student 
     INNER JOIN 
    fee_head2 ON (student.new_old = fee_head2.new_old) 
     INNER JOIN 
    fee_head2 ON (student.class = fee_head2.class) 
SET 
    student.head1_apr = fee_head2.head1_apr 

这是显示＃1066 - 非唯一表/别名：'fee_head2'。

任何人都可以纠正这个查询对我吗？

Answer 1

无需再加入同一个表，试试这个：

UPDATE student INNER JOIN fee_head2 
ON (student.new_old = fee_head2.new_old) 
AND (student.class = fee_head2.class) 
SET student.head1_apr = fee_head2.head1_apr 

Answer 2

阿齐兹打我明显naswer。

UPDATE student SET student.head1_apr = 
CASE 
    WHEN student.new_old = fee_head2.new_old AND student.class = fee_head2.class THEN fee_head2.head1_apr 
    ELSE NULL 
END