针对S_T数据库,查询既选修了1号课程又选修3号课程的学生,以下不正确的SQL命令是( )。
A.
select sno from sc where cno='1' and cno='3'
B.
select sno from sc where cno='1' intersect select sno from sc where cno='3'
C.
select sno from sc where cno='1' and sno in (select sno from sc where cno='3')
D.
select a.sno from sc a,sc b where a.sno=b.sno and a.cno='1' and b.cno='3'