sql - 如何获取从 Postgresql 中的子查询返回的结果总数？

Question

我正在尝试获取从子查询返回的结果总数。这是我的查询：

select 
    count(r.reason_id) as num,
    cast (count(r.reason_id) as float) / (select count(*) as total from r) * 100.0 as pct
from (
    select
        case
            when rarreason != 0 then rarreason
            else rejectreason end as reason_id
    from 
        workorderlines 
    where
        (rarreason != 0 or rejectreason != 0)
    ) as r

group by
    r.reason_id

但是，当我尝试执行此操作时，出现此错误：

ERROR:  relation "r" does not exist
LINE 3: ...on_id) as float) / (select count(*) as total from r) * 100.0...
                                                             ^

********** Error **********

ERROR: relation "r" does not exist
SQL state: 42P01
Character: 112

我该怎么做呢？我正在使用 Postgresql 9.1。谢谢！

Answer 1

尝试：

select 
    count(r.reason_id) as num,
    cast (count(r.reason_id) as float) / max(r.count_all) * 100.0 as pct
from (
    select
        case
            when rarreason != 0 then rarreason
            else rejectreason end as reason_id,
        count(*) over () as count_all
    from 
        workorderlines 
    where
        (rarreason != 0 or rejectreason != 0)
    ) as r

group by
    r.reason_id

Answer 2

没有检查您的逻辑，但您可以像这样重新排列它：

with r as (
    select
        case
            when rarreason != 0 then rarreason
            else rejectreason end as reason_id
    from 
        workorderlines 
    where
        (rarreason != 0 or rejectreason != 0)
)
select 
    count(r.reason_id) as num,
    cast (count(r.reason_id) as float) / (select count(*) as total from r) * 100.0 as pct
from r
group by r.reason_id