带有条件的多列结果的 SQL 选择答案

【问题标题】：SQL Select with multiple column result with conditions带有条件的多列结果的 SQL 选择
【发布时间】：2021-11-02 05:41:59
【问题描述】：

请帮助我处理这个 SQL 选择查询。它可以作为三个 select 语句，但我需要将它变成一个语句

select (loan_amount + origination_fee) column1 from Table
where transaction_type='A'

select (stock_price + broker_fee) column2 from Table
where transaction_type='B'

select (taxable_amount + miscellaneous) column3 from Table
where transaction_type='C'

我试过了：

SELECT   (
            SELECT  (loan_amount + origination_fee)
            FROM    table
            WHERE   transaction_type = 'A'
         ) AS A
        ,(
            SELECT  (stock_price + broker_fee)
            FROM    table
            WHERE   transaction_type = 'B'
         ) AS B
        ,(
            SELECT  (taxable_amount + miscellaneous)
            FROM    table
            WHERE   transaction_type = 'C'
         ) AS C

我收到以下错误：

消息 512，第 16 级，状态 1，第 1 行

子查询返回超过 1 个值。当子查询跟随 =、!=、、>= 或子查询用作表达式时，这是不允许的。

【问题讨论】：

样本数据有助于您的问题。
除了样本数据和想要的结果，还请为您正在使用的数据库添加标签。

标签： sql select subquery

【解决方案1】：

select case when transaction_type='A' then loan_amount + origination_fee end as A,
       case when transaction_type='B' then stock_price + broker_fee end as B,
       case when transaction_type='C' then taxable_amount + miscellaneous end as C 
from your_table

【讨论】：

【解决方案2】：

select case when transaction_type='A' then loan_amount + origination_fee else NULL end as A,
       case when transaction_type='B' then stock_price + broker_fee else NULL end as B,
       case when transaction_type='C' then taxable_amount + miscellaneous else NULL end as C 
from your_table
where transaction_type in ('A', 'B', 'C');

【讨论】：

【解决方案3】：

我不确定你到底想要什么。但是如果你想要一行包含三个值的 sum，那么：

select sum(case when transaction_type = 'A' then loan_amount + origination_fee end) as A,
       sum(case when transaction_type = 'B' then loan_amount + origination_fee end) as B,
       sum(case when transaction_type = 'C' then loan_amount + origination_fee end) as C
from t;

【讨论】：