//tham khao http://dungcoj.blogspot.com/2011/05/backup-va-restore-db-sql-trong-lap.html
//backup
public static bool DuLieuSaoLuu(string duongdan)
{
string sql = string.Format("BACKUP DATABASE [QLBH_CK] TO DISK='{0}'", duongdan);
return(DL_LayDuLieu.Backup(sql));
}