namespace MyDll
{
public partial class MyClass
{
[sqlMethod]
public static sqlString UrlDecode(string value)
{
return new sqlString(HttpUtility.UrlDecode(value));
}
}
}

EXEC sp_configure 'show advanced options','1';
GO
RECONFIGURE;
GO
EXEC sp_configure 'clr enabled','1'
RECONFIGURE;
GO

ALTER DATABASE DBName SET TRUSTWORTHY ON
GO

CREATE ASSEMBLY
[System.Web] FROM
'C:\WINDOWS\Microsoft.NET\Framework64\v2.0.50727\System.Web.dll'
WITH permission_set = UNSAFE
GO

CREATE ASSEMBLY sql_CLR_Url
FROM 'C:\MyDLL.dll'
WITH PERMISSION_SET = UNSAFE

GO

CREATE FUNCTION sqlUrlDecode(@urlstr NVARCHAR(4000))
RETURNS NVARCHAR(4000)
AS
EXTERNAL NAME sql_CLR_Url.[sqlClr.MyClass].UrlDecode
GO

select dbo.sqlUrlDecode(Name) from Table