Question

我正在尝试在select语句中计算一个值，但令人惊讶的是它会导致0。

SELECT Top(1) Name, 
LEN(Name) AS Equals, 
Abs(LEN('Johny') - LEN(Name)) AS NotEquals, 
LEN(Name)/(Abs(LEN('Johny') - LEN(Name)) + LEN(Name)) As Match
FROM Demo
WHERE Name = LEFT( 'Johny' , LEN(Name) ) 
ORDER BY LEN(Name) DESC

输出：

Name    Equals  NotEquals   Match
John    4           1         0

为什么输出中match字段0的确切值是什么？

Answer 1

因为你的计算使用整数：

4/5 = 0

删除逗号后面的所有内容

Answer 2

这是：

LEN(Name)/(Abs(LEN('Johny') - LEN(Name)) + LEN(Name)) As Match

4 / ((5 - 4) + 4)

4/ (1 + 4)

4 / 5

= 0

Answer 3

你试图划分整数值，其中除数＆gt;分红

尝试将一个值转换为float

SELECT Top(1) Name, 
LEN(Name) AS Equals, 
Abs(LEN('Johny') - LEN(Name)) AS NotEquals, 
cast(LEN(Name) as float)/(Abs(LEN('Johny') - LEN(Name)) + LEN(Name)) As Match
FROM Demo
WHERE Name = LEFT( 'Johny' , LEN(Name) ) 
ORDER BY LEN(Name) DESC

在select语句t-sql中计算值

3 个答案: