Question

关于分页的SQL语句问题，高手帮帮忙

语句如下，错误：单行子查询返回多个行，不知怎么改，请高手帮帮忙
select * from (
select row_.*, rownum rownum_ from (
select PROBLEM_ID as problem_id, PROBLEM_NAME as problem_name, PROBLEM_CONTENT as problem_content, USER_ID as user_id
, (select u.user_name from usertable u where u.user_id = t.user_id) as user_name
, (select c.attr_name from c_attr c where c.remark1 = t.lingyu) as lingyu
, IS_OPEN as is_open, IS_ASSIGN as is_assign, PROBLEM_TYPE as problem_type, IS_CHECK as is_check
, (select tt.name from testtree tt where tt.id = t.professional_id) as professional_name
, to_char(problem_date,'YYYY-MM-DD') as problem_date, is_answer as is_answer
from (select * from problem_list order by PROBLEM_DATE desc ) t
where t.is_difficute = '是'
and is_answer='否'
)row_ where rownum<=30
) where rownum_>=21
....数据库表结构问题 谁随便回答下 让我结贴吧

Answer 1

单行子查询返回多个行
可能是： (select c.attr_name from c_attr c where c.remark1 = t.lingyu) 这出错了 c.remark1 不是唯一的 决定查出的结果是多个。
为什么不用多表关联呢