i have some doubt ..in here this is the sequence number generatingeg:SGC24DOC000001

   public async Task<Service> GetDocnumber(Service service)
        {
            try
            {
                using (var db = new Hr_Entities())
                {
                    var nextValQuery = "SELECT SAFARIHR.HR_DOC_NO.NEXTVAL FROM DUAL";
                    var nextVal = await db.Database.SqlQuery<decimal>(nextValQuery).FirstOrDefaultAsync();
                    var today = DateTime.Now;
                    var lastTwoDigitsOfYear = today.Year % 100;
                    var seqNumber = nextVal.ToString().PadLeft(6, '0');
                    var DocumentNumber = $"SGC{lastTwoDigitsOfYear:00}DOC{seqNumber}";

                    service.Response = DocumentNumber;
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
            return service;
        }

   public async Task<Service> GetDocnumber(Service service)
        {
            try
            {
                using (var db = new Hr_Entities())
                {
                    var nextValQuery = "SELECT SAFARIHR.HR_DOC_NO.NEXTVAL FROM DUAL";
                    var nextVal = await db.Database.SqlQuery<decimal>(nextValQuery).FirstOrDefaultAsync();
                    var today = DateTime.Now;
                    var lastTwoDigitsOfYear = today.Year % 100;
                    var seqNumber = nextVal.ToString().PadLeft(6, '0');
                    var DocumentNumber = $"SGC{lastTwoDigitsOfYear:00}DOC{seqNumber}";

                    service.Response = DocumentNumber;
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
            return service;
        }

CREATE SEQUENCE SAF.HR_DOC_NO
  START WITH 16
  MAXVALUE 999999999999999999999999999
  MINVALUE 1
  NOCYCLE
  NOCACHE
  NOORDER;

CREATE SEQUENCE SAF.HR_DOC_NO
  START WITH 16
  MAXVALUE 999999999999999999999999999
  MINVALUE 1
  NOCYCLE
  NOCACHE
  NOORDER;