Question

对于此TSQL查询：

SELECT CAST(116.33 / 8 AS FLOAT) AS [Float Value]
 , LEN(CAST(116.33 / 8 AS FLOAT)) AS [Length of Float Value]
 , LEN(CAST(CAST(116.33 / 8 AS FLOAT) AS VARCHAR)) AS [Length Cast As Varchar]

结果：

Float Value  | Length of Float Value  |  Length Cast As Varchar
14.54125     | 7                      |  7

当我转换为Varchar时，为什么LEN会产生7而不是8？另外，隐式转换或转换会为LEN产生8？

Answer 1

Len function on Float in SQLServer gives wrong length非常相关，@ rbr94的答案很好地解释了这一点：

LEN（）适用于[N] VARCHAR（），因此您正在进行从FLOAT到VARCHAR的隐式转换

通过扩展您的查询可以轻松证明：

SELECT CAST(116.33 / 8 AS FLOAT) AS [Float Value]
 , LEN(CAST(116.33 / 8 AS FLOAT)) AS [Length of Float Value]
 , LEN(CAST(CAST(116.33 / 8 AS FLOAT) AS VARCHAR)) AS [Length Cast As Varchar]
 , CAST(CAST(116.33 / 8 AS FLOAT) AS VARCHAR) AS [Cast As Varchar]

给出了

Float Value Length of Float Value   Length Cast As Varchar  Cast As Varchar
14.54125    7                       7                       14.5413

Answer 2

如果我错了，请纠正我，但浮标的标准精度是7，因此这可能是你的问题。

首先将结果转换为float，结果为7位数。

请查看此微软post

Answer 3

隐式转换 - 看到这个链接

https://social.msdn.microsoft.com/Forums/en-US/a4ea2bc1-6f2f-4992-8132-f824fe4ffce0/length-of-float-values-in-ms-sql-server-gives-wrong-result?forum=transactsql

为什么SQL Len函数会为此查询返回7？

3 个答案: