子查询返回多行答案

【问题标题】：sub query return more than one row子查询返回多行
【发布时间】：2016-08-24 04:20:21
【问题描述】：

 select id, first_name, family_name, eq_id,
        date_of_birth, gender, indigenous, eal_d,
        atsi, icp, disability_category,
        (select raw_score
         from path_maths_term0 as T0
         where T0.eq_id=S.eq_id and year=2011
        ) as raw_score_2011term1,
       (select raw_score 
        from path_maths_term0 as T0
        where T0.eq_id=S.eq_id and year=2011
       ) as raw_score_2011term1,
       (select scale_score 
        from path_maths_term0 as T0
        where T0.eq_id=S.eq_id and year=2011
       ) as scale_score_2011term1,
       (select percentile 
        from path_maths_term0 as T0
        where T0.eq_id=S.eq_id and year=2011
       ) as percentile_2011term1,
       (select stanine 
        from path_maths_term0 as T0
        where T0.eq_id=S.eq_id and year=2011 
      ) as stanine_2011term1,
      class 
      from student_details as S
      where S.school_id ="SCH00001" and S.class = " 5B"

【问题讨论】：

任何正文都可以帮助我了解在哪里更改此查询
在查询中使用LIMIT 1
非常感谢它的工作！
你为什么使用子查询和查询表path_maths_term0 5 次，你可以使用连接在 1 个镜头中完成？

标签： php mysql codeigniter mysqli codeigniter-3

【解决方案1】：

在您的子查询中使用LIMIT 1，例如

select raw_score from path_maths_term0 as T0 where T0.eq_id=S.eq_id and year=2011 LIMIT 1

【讨论】：

【解决方案2】：

试试这个

select id, first_name, family_name, eq_id, date_of_birth, gender, indigenous, eal_d, atsi, icp, disability_category,

(select raw_score from path_maths_term0 as T0 where T0.eq_id=S.eq_id and T0.year=2011 ) as raw_score_2011term1,
(select scale_score from path_maths_term0 as T0 where T0.eq_id=S.eq_id and T0.year=2011 ) as scale_score_2011term1,

(select percentile from path_maths_term0 as T0 where T0.eq_id=S.eq_id and T0.year=2011 ) as percentile_2011term1,

(select stanine from path_maths_term0 as T0 where T0.eq_id=S.eq_id and T0.year=2011 ) as stanine_2011term1,
class from student_details as S
 where S.school_id ="SCH00001" and S.class = " 5B"

【讨论】：