4

我正在从 SQL Server 数据库中检索已签名的 int，并且需要将其转换为“正常”外观的虚线字符串以显示给用户。

谷歌搜索，我发现了这段代码：

SELECT 
   dbo.IPADDRESS.IPADDRESS,
   CAST(ROUND( (cast(dbo.IPADDRESS.IPADDRESS as bigint) / 16777216 ), 0, 1) AS varchar(4)) + '.' +
   CAST((ROUND( (cast(dbo.IPADDRESS.IPADDRESS as bigint) / 65536 ), 0, 1) % 256) AS varchar(4)) + '.' +
   CAST((ROUND( (cast(dbo.IPADDRESS.IPADDRESS as bigint) / 256 ), 0, 1) % 256) AS varchar(4)) + '.' + 
   CAST((cast(dbo.IPADDRESS.IPADDRESS as bigint) % 256 ) AS varchar(4)) as IPDottedNotation
FROM  
   dbo.IPADDRESS

这在某些时候有效，但在其他时候会产生古怪的输出。例如，转换 this-1951276725会产生 result -116.-78.-30.-181。

有什么建议么？谢谢。

4

3 回答 3

9 
DECLARE @IPADDRESS TABLE (
  IPADDRESS INT);

INSERT INTO @IPADDRESS
VALUES      (-1139627840),
            ( 1);

SELECT 
        LTRIM(CAST(SUBSTRING(IP,4,1) AS TINYINT)) + '.' + 
        LTRIM(CAST(SUBSTRING(IP,3,1) AS TINYINT)) + '.' + 
        LTRIM(CAST(SUBSTRING(IP,2,1) AS TINYINT)) + '.' + 
        LTRIM(CAST(SUBSTRING(IP,1,1) AS TINYINT))
FROM @IPADDRESS
CROSS APPLY (SELECT CAST(IPADDRESS AS BINARY(4))) C(IP)

在此处输入图像描述

于 2012-06-24T13:15:23.497 回答
3

如果IPADDRESS是 bigint（有效地将 unsigned int 表示形式存储在数据库中 - 即所有值 > 0），您拥有的代码将可以工作。您可以选择更改表中的数据类型吗？

要获得您必须工作的内容，您需要在转换为 bigint 之前将您的有符号整数转换为等效的无符号整数。我不确定在 TSQL 中执行此操作的最有效方法是什么，但可能是将其转换为二进制：

SELECT dbo.IPADDRESS.IPADDRESS,
CAST(ROUND( (cast(cast(dbo.IPADDRESS.IPADDRESS as binary(4)) as bigint) / 16777216 ), 0, 1) AS varchar(4)) + '.' +
CAST((ROUND( (cast(cast(dbo.IPADDRESS.IPADDRESS as binary(4)) as bigint) / 65536 ), 0, 1) % 256) AS varchar(4)) + '.' +
CAST((ROUND( (cast(cast(dbo.IPADDRESS.IPADDRESS as binary(4)) as bigint) / 256 ), 0, 1) % 256) AS varchar(4)) + '.' + 
CAST((cast(cast(dbo.IPADDRESS.IPADDRESS as binary(4)) as bigint) % 256 ) AS varchar(4)) as IPDottedNotation
于 2012-06-24T13:15:03.573 回答
1

就像@Ed Harper 所说的那样，所选解决方案不适用于有符号整数。下面是我的解决方案，它需要更少的铸造并且没有倒置。查看下面显示的以下测试场景，其中转换后的字符串/varchar IP 应为 192.168.18.188：

CREATE TABLE #data
  (
     ip     NVARCHAR(45),
     before NVARCHAR(45)
  )

INSERT INTO #data
VALUES     ('converted-ip','-1139627840')

    update #data
    set ip = cast((cast(before as int) & 255) as nvarchar) + '.' +
         cast((cast(floor(convert(decimal, before)/256) as int) & 255) as nvarchar) + '.' +
         cast((cast(floor(convert(decimal, before)/65536) as int) & 255) as nvarchar) + '.' +
         cast((cast(floor(convert(decimal, before)/16777216) as int) & 255) as nvarchar)

select * from #data
于 2016-05-10T14:49:10.477 回答