private static readonly SqlConnection CnnGlobal = new SqlConnection();

        private static SqlConnection conDB()
        {
            if ((CnnGlobal.State == ConnectionState.Closed) | (CnnGlobal.State == ConnectionState.Broken))
            {
                try
                {

                    CnnGlobal.ConnectionString = (
                                                    "Data Source=" + ServerSql + 
                                                    ";Initial Catalog=" + ServerSqlBase + 
                                                    ";User ID=" + ServerSqlLogin + 
                                                    ";Password=" + ServerSqlPass
                                                );
                    CnnGlobal.Open();
                }
                catch (Exception ex)
                {
                    var frame = new StackFrame(0);
                    const string strAction = "Ошибка";
                    var strParam = ex.Message;
                    ClsMain.log(strAction, strParam, frame.GetMethod().Name, true);
                    return null;
                }
            }
            
            return CnnGlobal;
        }