string req="Select * from table";

        public void RetData(string req, DataGridView GRID)
        {
            FbCommand sqlReqest = new FbCommand(req, FBConection);
            FbDataAdapter ad = new FbDataAdapter(sqlReqest);
            DataTable dt = new DataTable();
            ad.Fill(dt);
            GRID.Rows.Clear();
            GRID.Columns.Clear();
            int ColCount=dt.Columns;


            for (int Q = 0; Q <ColCount; Q++)              GRID.Columns.Add(new DataGridViewTextBoxColumn());
            GRID.Rows.Add(dt.Rows.Count);
             
            for (int R=0;R<dt.Rows.Count;R++)
               for (int Col = 0; Col <ColCount; Col++)
                    GRID[Col,R].Value=dt.Rows[R].ItemArray[Col].ToString();
         }