Code
using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.Text.RegularExpressions;
// 示意代碼
public partial class UserDefinedFunctions
{
    public static readonly RegexOptions Options = 
RegexOptions.IgnorePatternWhitespace | RegexOptions.Singleline;
    [Microsoft.SqlServer.Server.SqlFunction]
    public static string RegexValue(SqlChars input, SqlString pattern)
    {
        Regex regex = new Regex(pattern.Value, Options);
        return  regex.Match(new string(input.Value)).Value;
    }
}

EXEC sp_configure 'clr enabled', 1
sql 如下：
select dbo.RegexValue('2008-09-02',N'\d{4}') from Table
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