datagridview 上一条数据，下一条数据实现

private void button2_Click(object sender, EventArgs e)
        {
            if (dataGridView1.CurrentCell.RowIndex !=0)
            {
                dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
                this.dataGridView1.CurrentCell = this.dataGridView1[this.dataGridView1.CurrentCell.ColumnIndex, this.dataGridView1.CurrentCell.RowIndex - 1];
                textBox1.Text = dataGridView1.Rows[dataGridView1.CurrentCell.RowIndex].Cells[0].Value.ToString();
            }
            else
            {
                MessageBox.Show("第一条数据");
            }
        }

        private void button3_Click(object sender, EventArgs e)
        {
            if (dataGridView1.CurrentCell.RowIndex != dataGridView1.RowCount - 1)
            {
                dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
                this.dataGridView1.CurrentCell = this.dataGridView1[this.dataGridView1.CurrentCell.ColumnIndex, this.dataGridView1.CurrentCell.RowIndex + 1];
                textBox1.Text = dataGridView1.Rows[dataGridView1.CurrentCell.RowIndex].Cells[0].Value.ToString();
            }
            else
            {
                MessageBox.Show("最后一条记录");
            }
        }