两个相同的sql为什么一个能执行一个报错

Question

SELECT sno,sname FROM student WHERE sno NOT IN ( SELECT sno FROM sc INNER JOIN course on sc.cno=course.cno INNER JOIN teacher ON teacher.tno=course.tno WHERE teacher.tname='小1老师');

SELECT sno,sname FROM student WHERE sno NOT IN ( SELECT sno FROM sc INNER JOIN course on sc.cno=course.cno INNER JOIN teacher ON teacher.tno=course.tno WHERE teacher.tname='小1老师');

 

第二个sql是正确答案，能执行，第一个是我比着答案写的，看着和答案完全一样，但是执行报错，好奇怪，怎么回事？

Answer 1

报什么错