验证开始日期和结束日期

/// <summary>
        /// 验证结束日期大于等于开始日期
        /// </summary>
        /// <param name="startDate">开始日期</param>
        /// <param name="endDate">结束日期</param>
        /// <param name="curDbField">验证日期对应的数据库字段</param>
        /// <param name="filterExpression">条件</param>
        /// <returns>true/false</returns>
        private bool ValidOracleStartEndDate(string startDate, string endDate, string curDbField, out string filterExpression)
        {
            filterExpression = string.Empty;
            string startDateFilter = " AND {1} >= to_date('{0}','YYYY-MM-DD HH24:MI:SS') ";
            string endDateFilter = " AND {1} < to_date('{0}','YYYY-MM-DD HH24:MI:SS') ";

            // 开始、结束日期为空
            if ((startDate == null || startDate.Length == 0) && (endDate == null || endDate.Length == 0))
            {
                return true;
            }

            DateTime sDate = WebCommon.ToStartDateTime(startDate);
            DateTime eDate = WebCommon.ToEndDateTime(endDate);

            // 开始日期大于结束日期
            if (sDate > eDate)
            {
                return false;
            }
            else // 开始日期小于等于结束日期（正确）
            {
                eDate = eDate == DateTime.MaxValue ?
                    DateTime.MaxValue : eDate.AddDays(1);
                filterExpression = string.Format(startDateFilter, sDate, curDbField);
                filterExpression += string.Format(endDateFilter, eDate, curDbField);
                return true;
            }
        }

        /// <summary>
        /// 验证结束日期大于等于开始日期
        /// </summary>
        /// <param name="startDate">开始日期</param>
        /// <param name="endDate">结束日期</param>
        /// <param name="curDbField">验证日期对应的数据库字段</param>
        /// <param name="filterExpression">条件</param>
        /// <returns>true/false</returns>
        public static bool ValidSqlServerStartEndDate(string startDate, string endDate, string curDbField, out string filterExpression)
        {
            filterExpression = string.Empty;
            string startDateFilter = " AND convert(varchar(10),{1},120) >= '{0}' ";
            string endDateFilter = " AND convert(varchar(10),{1},120) < '{0}' ";

            // 开始、结束日期为空
            if ((startDate == null || startDate.Length == 0) && (endDate == null || endDate.Length == 0))
            {
                return true;
            }

            DateTime sDate = Object2StartDate(startDate);
            DateTime eDate = Object2EndDate(endDate);

            // 开始日期大于结束日期
            if (sDate > eDate)
            {
                return false;
            }
            else // 开始日期小于等于结束日期（正确）
            {
                eDate = eDate == DateTime.MaxValue ?
                    DateTime.MaxValue : eDate.AddDays(1);
                filterExpression = string.Format(startDateFilter, sDate.ToString("yyyy-MM-dd"), curDbField);
                filterExpression += string.Format(endDateFilter, eDate.ToString("yyyy-MM-dd"), curDbField);
                return true;
            }
        }