如何根据其他列的条件创建列计算查询 [英] How to create query with column computation based on condition from other column

问题描述

您好我有一张SQL表：

Hi I have a SQL table:

SrNo Name     Amount  ApplyTax
1    John     500      Yes 
2    Peter    700      No
3    Tom      900      Yes

如果我想对那些将ApplyTax作为1的人征收20％的税，我该怎么做一个查询：



我需要的输出是

If I want to levy tax at 20% on those who have ApplyTax as 1, how do I do that in one query:

The output I need is

SrNo Name     Amount  Tax
1    John     500      100
2    Peter    700      0
3    Tom      900      180

我是SQL新手所以任何帮助都会太棒了



谢谢，

T

I am new to SQL so any help would be great.

Thanks,
T

推荐答案

试试这个，

Try this,

select SrNo,Name,Amount,case when ApplyTax='Yes' then (Amount*0.2) else 0 end as Tax  from Table

这里我使用了（金额* 0.2），其中相当于金额的20％。

Here I have used (Amount*0.2), which is equal to 20% of Amount.

20% Amount = (Amount/100)*20

您可以使用案例声明

https：/ /msdn.microsoft.com/en-us/library/ms181765.aspx [ ^ ]

You can use Case Statement
https://msdn.microsoft.com/en-us/library/ms181765.aspx[^]

select SrNo,name ,Amount,case when ApplyTax='Yes' then (Amount*20)/100 when ApplyTax='No' then 0 end as Tax From table_name 

尝试：

Try:

SELECT SrNo, Name, Amount, 
   CASE WHEN ApplyTax='Yes' THEN (Amount * 20) / 100 ELSE 0       
   END AS Tax 
FROM MyTable

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