Question

在previous post中，有人帮助我进行了子查询。现在，我想添加到查询中，但收到一条错误消息。（我仍在学习有关子查询的规则。）

下面更新了SQL。错误是：

[Amazon](500310) Invalid operation: invalid reference to FROM-clause entry for table "application_stages";

SELECT t1.*, applications.status, applications.stage_name
FROM application_stages t1
JOIN (
    select application_id, max(exited_on) as exited_on
    from application_stages 
    group by application_id
) t2 
USING (application_id,exited_on)
join applications on application_stages.application_id = applications.id
where application_id in ('91649746', '91991364', '96444221')

Answer 1

为此使用窗口功能：

select ast.*, a.status, a.stage_name
from (select ast.*,
             rank() over (partition by application_id order by exited_on desc) as seqnum
      from application_stages ast
     ) ast join
     applications a
     on ast.application_id = a.id
where ast.seqnum = 1 and
      ast.application_id in ('91649746', '91991364', '96444221');

您的查询有几个问题：

application_id

where不明确
application_stages的别名为t1，因此无法识别前者

请注意，如果application_id是一个数字（我猜是这种情况），则常量不应使用单引号。

Answer 2

分配别名时，需要在所有子句中一致使用它们，并避免在其他表中使用相同名称的列引起歧义。考虑进行以下调整

SELECT s.*, a.status, a.stage_name
FROM application_stages s
JOIN (
    select application_id, max(exited_on) as exited_on
    from application_stages 
    group by application_id
) m 
USING (application_id, exited_on)
JOIN applications a ON a.application_id = s.id
WHERE a.application_id IN ('91649746', '91991364', '96444221')

将表联接到子查询

2 个答案: