sql - 我想编写一个汇总查询并将结果显示在一个表中

Question

我需要编写一份关于 3 个不同状态值的摘要报告，每个状态都有一个计数和一个金额列，结果显示在一个表格中。例如，输出将如下所示:

生成每行代码(在单个输出中)的查询是:

select case when status_key = '2' then 'Paid' else '' end as 'Status'
, COUNT(BillNo) as [Count]
, SUM(amtpd) as [Amount Paid]
from billtable 
where client = 101
and status_key = '2'
group by status_key

select case when status_key = '1' then 'Queued' else '' end as 'Status'
, COUNT(BillNo) as [Count]
, SUM(amtpd) as [Amount Paid]
from billtable 
where client = 101
and status_key = '1'
group by status_key

select case when status_key = '4' then 'Hold' else '' end as 'Status'
, COUNT(BillNo) as [Count]
, SUM(amtpd) as [Amount Paid]
from billtable 
where client = 101
and status_key = '4'
group by status_key

这会产生三个结果，例如:

我正在使用 SQL Server 数据库和 SSMS 来开发查询。

Answer 1

不需要联合。

使用 WHERE 仅筛选出您想要的 status_keys，然后展开您的 CASE 语句以将数字重新编码为单词。

select
  case when status_key = '2' then 'Paid'
       when status_key = '1' then 'Queued'
       when status_key = '4' then 'Hold'
                             else 'Error!' end     AS [Status],
  COUNT(BillNo)                                    AS [Count],
  SUM(amtpd)                                       AS [Amount Paid]
from
  billtable
where
  client = 101
  AND status_key IN ('1','2','4')
group by
  status_key

EDIT 使用维度表修改示例

select
  status.description                                    AS [Status],
  COUNT(bill_table.BillNo)                              AS [Count],
  SUM(bill_table.amtpd)                                 AS [Amount Paid]
from
  billtable
inner join
  status
    on billtable.status_key = status.key
where
      bill_table.client      = 101
  AND bill_table.status_key IN ('1','2','4')
group by
  status.description

然后您可以拥有从status 到billtable 的外键约束。这将确保数据不能插入到billtable，除非在status中有相应的key。

您的查找将始终有效。但是，如果未正确填充 status 表，则会以插入失败的“成本”为代价。

这种事实表和维度表结构是关系数据库设计的基础。