关于查询当行返回多行
初学不是很懂，SELECT (SELECT answer FROM student1 WHERE student_id=85 ) sbp ,
(SELECT answer FROM student1 WHERE student_id=86 ) dbp
FROM student t_v WHERE enable_flag=1
结果显示单行自查询返回多个行，怎么理解
[解决办法]

--这个Query要干嘛啊...select 的column返回多行肯定报错SELECT (SELECT answer FROM student1 WHERE student_id=85 ) sbp 
      ,(SELECT answer FROM student1 WHERE student_id=86 ) dbp
  FROM student t_v 
 WHERE enable_flag=1

[解决办法]
子查询在select 上只能有1条结果
这样可以、

select (
        select 2
        from dual
       )  one_
from dual;

2个结果不行

select (
        select 2
        from dual
        connect by level<=2
       )  one_
from dual;

子查询放到select 不好
不如用Join