MySQL 1093

错误代码如下：

#(8) 把“邓维杰”同学的成绩全部删除。
SELECT * FROM sc WHERE EXISTS(SELECT * FROM student WHERE student.sno=sc.sno AND student.sname='邓维杰');
DELETE FROM sc WHERE degree IN(SELECT degree FROM sc WHERE sno=(SELECT sno FROM student WHERE sname='邓维杰'));

报错：

[SQL]DELETE FROM sc WHERE degree IN(SELECT degree FROM sc WHERE sno=(SELECT sno FROM student WHERE sname='邓维杰'));
[Err] 1093 - You can't specify target table 'sc' for update in FROM clause

百度原因：

update语句中包含的子查询的表和update的表为同一张表时
报错：1093-You can’t specify target table for update in FROM clause

mysql不允许update目标表和子查询里面的表为同一张表

解决方法：

1. e，就是不用同一张表呗（本人(小白)的解决方法。。）。
2. 大佬的方法是将子查询又嵌套了一层子查询（即外层的子查询不和父查询同一个表）。

修改后代码：

#(8) 把“邓维杰”同学的成绩全部删除。
SELECT * FROM sc WHERE EXISTS(SELECT * FROM student WHERE student.sno=sc.sno AND student.sname='邓维杰');
DELETE FROM sc WHERE sno IN (SELECT sno FROM student WHERE sname='邓维杰');

ok.

附大佬的解决方法：https://www.cnblogs.com/ghjbk/p/10456204.html