CLR实现阴历阳历转换

using System;
using System.Data.SqlTypes;
using System.Globalization;

public partial class UserDefinedFunctions
{
    [Microsoft.SqlServer.Server.SqlFunction]
    public static SqlString SolarToLunar(string time)
    {
        //转阴历
        ChineseLunisolarCalendar cncld = new ChineseLunisolarCalendar();
        DateTime dt = DateTime.Parse(time);
        int year = cncld.GetYear(dt);
        int flag = cncld.GetLeapMonth(year);
        int month = flag > 0 ? cncld.GetMonth(dt) - 1 : cncld.GetMonth(dt);
        int day = cncld.GetDayOfMonth(dt);

        int monthbk = month;
        if (flag > 0)
        {
            if (month < flag )
            {
                month = month + 1;
            }
            if (flag - 1 == monthbk)
            {
                month = month - 1;
            }
        }
        return $"{(flag-1 == monthbk ? "润" : "")}{year}-{(month.ToString().Length == 1 ? "0" + month : month + "")}-{(day.ToString().Length == 1 ? "0" + day : day + "")}";
    }

    [Microsoft.SqlServer.Server.SqlFunction]
    public static SqlString LunarToSolar(string time)
    {
        //转阳历
        bool rn = time.Contains("润");
        time = time.Replace("润", "");
        ChineseLunisolarCalendar cncld = new ChineseLunisolarCalendar();
        int year = Convert.ToInt32(time.Split('-')[0]);
        int month = Convert.ToInt32(time.Split('-')[1]);
        int day = Convert.ToInt32(time.Split('-')[2]);
        int flag = cncld.GetLeapMonth(year);

        int monthbk = month;
        if (flag > 0)
        {
            if ( month< flag)
            {
                if (!rn)
                {
                    month = month - 1;
                }
            }  
        }

        month += flag > 0 ? 1 : 0;
        DateTime dtnl = cncld.ToDateTime(year, month, day, 0, 0, 0, 0);
        return dtnl.ToString("yyyy-MM-dd");
    }

}