ccaxiは四半期のインスタンスコードを取得した（四半期の最初の日）

string firstDayOfThisQuarter = DateTime.Now.AddMonths(0-(DateTime.Now.Month - 1)%3).ToString("yyyy-MM-01");
Console.WriteLine("        ：{0}",firstDayOfThisQuarter);
string lastDayOfThisQuarter = DateTime.Parse(DateTime.Now.AddMonths(3 - ((DateTime.Now.Month - 1)%3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();
string lastDayOfThisQuarter2 = DateTime.Parse(DateTime.Now.AddMonths(3 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01")).AddDays(-1).ToString("yyyy-MM-dd");
Console.WriteLine("         ：{0}", lastDayOfThisQuarter);
Console.WriteLine("         ：{0}", lastDayOfThisQuarter2);
string firstDayOfNextQuarter = DateTime.Now.AddMonths(3 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01");
string lastDayOfNextQuarter = DateTime.Parse(DateTime.Now.AddMonths(6 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();
Console.WriteLine("        ：{0}", firstDayOfNextQuarter);
Console.WriteLine("         ：{0}", lastDayOfNextQuarter);
string firstDayOfLastQuarter = DateTime.Now.AddMonths(-3 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01");
string lastDayOfLastQuarter = DateTime.Parse(DateTime.Now.AddMonths(0 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();
Console.WriteLine("        ：{0}", firstDayOfLastQuarter);
Console.WriteLine("         ：{0}", lastDayOfLastQuarter);