SQL中的条件计算列

Posted 2023-05-08

【中文标题】SQL中的条件计算列

【英文标题】：Conditional Calculating Column in SQL

【发布时间】：2020-09-19 00:30:16

【问题描述】：

我在 SQL 中有一个名为Invoice 的表。

InvNo   Date     CustName   TypeOfSale  Tax        Grand
21      2019     AA         T1          $1.00      $10.00
22      2019     AA         T2          $2.00      $20.00
23      2019     BB         T1          $1.00      $10.00
24      2020     AA         T1          $1.00      $10.00
25      2020     BB         T1          $1.00      $10.00
26      2020     BB         T2          $2.00      $20.00  

我正在尝试执行显示下表的查询 在reselut中，我正在寻找按年收入以及销售类型 如果我假设Revenue = Grand - Tax 那么：

CustName    Revenue TypeT1 2019     Revenue TypeT2 2019    Revenue TypeT1 2020      Revenue TypeT2 2020
AA          $9.00                   $18.00                 $9.00                    $0.00
BB          $9.00                   $0.00                  $9.00                    $18.00

我真的很感谢任何帮助

【参考方案1】：

对于销售类型和年份的固定列表，您可以进行条件聚合：

select custname,
    sum(case when date = 2019 and typeofsale = 'T1' then grand - tax else 0 end) t1_2019,
    sum(case when date = 2019 and typeofsale = 'T2' then grand - tax else 0 end) t2_2019,
    sum(case when date = 2020 and typeofsale = 'T1' then grand - tax else 0 end) t1_2020,
    sum(case when date = 2020 and typeofsale = 'T2' then grand - tax else 0 end) t2_2020
from mytable
group by custname