选择内的条件选择答案

【问题标题】：conditional select inside select选择内的条件选择
【发布时间】：2021-11-07 22:02:49
【问题描述】：

select t.col1,b.somecolumn t.col2,a.col1,VQ.a,VQ.b,VQ.e,VQ.d,VQ.f,  
   (select t.status as a, p.id as b,p.permit as c, p.des as d, p.error_code as e, p.cause as f
   from table_A t 
   inner join table_B p on t.a = p.a 
   where p.c = 'license' and t.status = 'Fail') as VQ
  from table_A t 
  join table_C a on t.col1 = a.asset_id
  join table_B b on t.somecolumn = b.somecolumn ;

当我执行上面的代码时，我遇到了错误

SQL Error [42601]: ERROR: navigation on column "vq" is not allowed as it is not SUPER type

我正在尝试在 select 中进行选择。

【问题讨论】：

请解释你想要完成的逻辑。样本数据和期望的结果会有所帮助。

标签： sql postgresql select subquery

【解决方案1】：

您似乎想从相关子查询中返回多个列。如果是这样，您可以使用lateral join：

select t.col1, b.somecolumn t.col2, a.col1, vq.*
from table_A t join
     table_C a
     on t.col1 = a.asset_id join
     table_B b
     on t.somecolumn = b.somecolumn left join lateral
     (select t.status as a, p.id as b,p.permit as c, p.des as d, p.error_code as e, p.cause as f
      from table_A t join
           table_B p on t.a = p.a 
      where p.c = 'license' and t.status = 'Fail'
     ) vq
     on 1=1;

【讨论】：