C#

private void DataGridFill(bool isAccess, bool isOIS)
        {
            
            string connString, stbQuery;
            DataGridView dgv;
           
            if (isAccess)
            {
                connString = AccessConnString;
                stbQuery = String.Format("SELECT * FROM {0}", cmbboxAccessTables.Text );
                dgv = dgvAccess;
            }
            else
            {
                connString = SqlConnString;
                stbQuery = String.Format("SELECT * FROM {0}", cmbboxOISTables.Text);
                dgv = dgvOIS;
            }
            // open connection
            var conn = new OleDbConnection(connString);
            conn.Open();
            
            // create query

            //var sqlQuery = new OleDbCommand(stbQuery);
            //sqlQuery.Connection = conn;
           
            // create an OLEDbDataAdapter to execute query
            var dataAdapter = new OleDbDataAdapter(stbQuery, conn);

            //create a command builder
            OleDbCommandBuilder cb = new OleDbCommandBuilder(dataAdapter);
            
            //create a DataTable to hold the query results
            var data = new DataTable();
            
             // fill data adapter
            dataAdapter.Fill(data);

            // Set it back to something that allows us to set the datasource
            // Arbitrarily picked CellSelect
            // We change it back to FullColumnSelect later
            if (dgv.SelectionMode == DataGridViewSelectionMode.FullColumnSelect)
            {
                dgv.SelectionMode = DataGridViewSelectionMode.CellSelect;
            }

            // assign datasource
            dgv.DataSource = data;

            // must format before assigning data source or else we error (selection issues)
            FormatGrid(ref dgv);