Question

我正在尝试在SQL Server上运行此脚本：

CREATE FUNCTION [dbo].[IPAddressToCidr](@IP AS VARCHAR(15))
RETURNS INT
AS
BEGIN
    DECLARE @result INT;
    DECLARE @ipInt BIGINT;

    SET @ipInt = CONVERT(BIGINT, PARSENAME(@IP, 1)) + CONVERT(BIGINT, PARSENAME(@IP, 2)) * 256 + CONVERT(BIGINT, PARSENAME(@IP, 3)) * 65536 + CONVERT(BIGINT, PARSENAME(@IP, 4)) * 16777216;
    SET @result = CAST(( 32 - LOG(4294967296 - @ipInt, 2)) AS INT);

    RETURN @result;
END;

结果错误是：

Msg 174，Level 15，State 1，Procedure IPAddressToCidr，Line 11
log函数需要1个参数。

我正在努力......

SELECT LOG(4294967296,2)  /*this has problem*/
SELECT LOG(4294967296)    /*this one works but with different results */

Log()函数有两个参数的帮助吗？

Answer 1

SQL Server 2012+ 支持LOG(expr, [base])

使用较低版本，您可以使用简单的Math来获得结果：

SELECT LOG(1024)/LOG(2)   -- 10, 2 ^ 10  = 1024
SELECT LOG(1000)/LOG(10)  -- 3, 10 ^ 3   = 1000

的 LiveDemo

<强> Change of base formula

LOG(@arg,base) = LOG(@arg) / LOG(base)

日志功能在SQL服务器上需要1个参数

1 个答案: