DataGridView合并单元格(一列或一行)之一

        #region"合并单元格的测试(一列或一行)"
        // int?是搜索一种类型(可空类型)，普通的int不能为null，而用int?，其值可以为null 
        //private int? nextrow = null;
        //private int? nextcol = null;

        //在CellPainting方法后调用
        private void dataGridView1_CellFormatting(object sender, System.Windows.Forms.DataGridViewCellFormattingEventArgs e)
        {
            /*
            //列标示
            if (e.ColumnIndex >= 0 && this.dataGridView1.Columns[e.ColumnIndex].HeaderText == "PARENTID"  && e.RowIndex >= 0)
            {
                //若与下一行同列单元格值相同则修改设置
                if (e.RowIndex = 0 && this.dataGridView1.Columns[e.ColumnIndex].HeaderText == "PHONE1" && e.RowIndex >= 0)
            {
                //若与同行下一列单元格值相同则修改设置
                if (e.ColumnIndex != this.dataGridView1.ColumnCount - 1 && this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value != null)
                {
                    if (e.Value.ToString() == this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value.ToString())
                    {
                        e.CellStyle.BackColor = Color.LightBlue;
                        this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Style.BackColor = Color.LightPink;
                        this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].ReadOnly = true;
                        //this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].ReadOnly = true;
                    }
                }
            }
             */
        }

        //==========================

        //绘制单元格
        private void dataGridView1_CellPainting(object sender, System.Windows.Forms.DataGridViewCellPaintingEventArgs e)
        {
            //纵向合并
            if (e.ColumnIndex >= 0 && this.dataGridView1.Columns[e.ColumnIndex].HeaderText == "PARENTID"  && e.RowIndex >= 0)
            {
                using (
                    Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor),
                    backColorBrush = new SolidBrush(e.CellStyle.BackColor))
                {
                    using (Pen gridLinePen = new Pen(gridBrush))
                    {
                        // 擦除原单元格背景
                        e.Graphics.FillRectangle(backColorBrush, e.CellBounds);

                        /****** 绘制单元格相互间隔的区分线条，datagridview自己会处理左侧和上边缘的线条，因此只需绘制下边框和和右边框
                         DataGridView控件绘制单元格时，不绘制左边框和上边框，共用左单元格的右边框，上一单元格的下边框*****/
                        
                        //不是最后一行且单元格的值不为null
                        if (e.RowIndex = 0 && this.dataGridView1.Columns[e.ColumnIndex].HeaderText == "PHONE1" && e.RowIndex >= 0)
            {
                using (
                    Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor),
                    backColorBrush = new SolidBrush(e.CellStyle.BackColor))
                {
                    using (Pen gridLinePen = new Pen(gridBrush))
                    {
                        // 擦除原单元格背景
                        e.Graphics.FillRectangle(backColorBrush, e.CellBounds);

                        /****** 绘制单元格相互间隔的区分线条，datagridview自己会处理左侧和上边缘的线条，因此只需绘制下边框和和右边框
                         DataGridView控件绘制单元格时，不绘制左边框和上边框，共用左单元格的右边框，上一单元格的下边框*****/

                        //不是最后一列且单元格的值不为null
                        if (e.ColumnIndex