C#获取开始时间结束时间月份区间的年月集合

数据库数据列为2021-05的字符串格式，想取2021-05-2021-07数据库月份范围区间符合条件的数据，由于用的是传统的EF查询写法，找了大半天，发现没找到List条件开始时间和结束时间的月份集合，最终参考辅助方法解决了问题，赶紧发出来以防下次踩坑。

    /// <summary>
    /// 计算年月区间
    /// </summary>
    public class ComputeDate
    {
        /// <summary>
        /// 年
        /// </summary>
        public int Year { get; set; }  
        /// <summary>
        /// 月
        /// </summary>
        public int Month { get; set; } 
    }

        /// <summary>
        /// 计算区间月份
        /// </summary>
        /// <param name="startYear">开始年</param>
        /// <param name="startMonth">开始月</param>
        /// <param name="endYear">结束年</param>
        /// <param name="endMonth">结束月</param>
        /// <returns></returns>
        public List<string> ComputeMonth(int startYear, int startMonth, int endYear, int endMonth)
        {
            List<ComputeDate> ComputeDateList = new List<ComputeDate>();   //计算的区间结果存放在集合
            List<string> ymList = new List<string>();
            if (startYear <= endYear)
            {
                int ComputeYear = endYear - startYear;  //计算开始年和结束年差值
                if (ComputeYear > 0)//跨年情况
                {
                    //循环开始年到结束年
                    for (int i = startYear; i <= startYear + ComputeYear; i++)
                    {
                        if (i == endYear)
                        {
                            for (int lastYear = 1; lastYear <= endMonth; lastYear++)
                            {
                                ComputeDateList.Add(new ComputeDate() { Year = i, Month = lastYear });
                            }
                        }
                        else
                        {
                            if (i == startYear)
                            {
                                for (int lastMonth = startMonth; lastMonth <= 12; lastMonth++)
                                {

                                    ComputeDateList.Add(new ComputeDate() { Year = i, Month = lastMonth });
                                }
                            }
                            else
                            {
                                for (int quyue = 1; quyue <= 12; quyue++)
                                {
                                    ComputeDateList.Add(new ComputeDate() { Year = i, Month = quyue });
                                }
                            }
                        }
                    }
                }
                else
                {
                    //同年情况
                    for (int i = startMonth; i <= endMonth; i++)
                    { 
                        ComputeDateList.Add(new ComputeDate() { Year = startYear, Month = i });
                    }
                }
             
                foreach (var item in ComputeDateList)
                {
                    //发现月份会少0，判断小于10月补0
                    var months = "";
                    if (item.Month<10) {
                        months = "0"+item.Month;
                    }
                    else{ 
                        months = Convert.ToString(item.Month);
                    }
                    ymList.Add(item.Year + "-" + months);
                }
            }
            return ymList;
        }


        /// <summary>
        /// 条件过滤
        /// </summary>
        /// <param name="query"></param>
        /// <returns></returns>
        public IQuery<BankCorpOCRecord> ConditionFilter(IQuery<BankCorpOCRecord> query)
        {
            if (!string.IsNullOrEmpty(OrgName))
            {
                query = query.Where(x => x.OrgName.Contains(OrgName));
            }
            if (!string.IsNullOrEmpty(BankAccount))
            {
                query = query.Where(x => x.BankAccount == BankAccount);
            }
            if (!string.IsNullOrEmpty(BankAccountName))
            {
                query = query.Where(x => x.BankAccountName.Contains(BankAccountName));
            }
            if (!string.IsNullOrEmpty(beginTime))
            {

                int startYear = Convert.ToInt32(beginTime.Substring(0,4));   //开始年份
                int startMonth = Convert.ToInt32(beginTime.Substring(5, 2));   //开始月份
                int endYear = Convert.ToInt32(endTime.Substring(0, 4));    //结束年份
                int endMonth = Convert.ToInt32(endTime.Substring(5, 2));      //结束月份  
                ReconciliationDataHelper helper = new ReconciliationDataHelper(); 
                var PeriodList = helper.ComputeMonth(startYear, startMonth, endYear, endMonth); 
                query = query.Where(x => PeriodList.Contains(x.PERIOD));
            }
            return query;
        }