Winform datagridview中显示下拉框

有时在datagridview中会显示下拉框，方便修改数据，但又不想有下拉框的列在浏览状态全显示有下拉框，如果多列有下拉框会非常难看，

因此就用combox的显示与否来控制，如下图(Factory_ID显示工厂ID号，当此列的单元格获取焦点时，此单元格显示下拉框)

代码如下：

public partial class Form1 : Form
    {  
        private static  string oraclestr = @"(DESCRIPTION =
                                                (ADDRESS_LIST =
                                                   (ADDRESS = (PROTOCOL = TCP)(HOST = 10.1.225.255)(PORT = 1521))
                                                 )
                                                 (CONNECT_DATA =
                                                    (SERVICE_NAME = testdb)
                                                 )
                                               )";

       static   string ConnectStr = string.Format("Data Source={0};User ID={1};Password={2}", oraclestr,"userid","password");
        DataTable dt = new DataTable();
        DataTable dtlst = new DataTable();
        OracleConnection conn = new OracleConnection(ConnectStr);

        private DataTable GetTable(string sql)
        {
            DataTable dt = new DataTable();
            try
            {
                conn.Open();
                OracleCommand cmd = conn.CreateCommand();
                cmd.CommandText = sql;
                cmd.CommandType = CommandType.Text;
                OracleDataAdapter oda = new OracleDataAdapter(cmd);
                oda.Fill(dt);
            }
            catch(Exception ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                conn.Close();
            }
            return dt;
        }
        public Form1()
        {
            InitializeComponent();
        }
    
    
        private void Form1_Load(object sender, EventArgs e)
        {
            dataGridView1.DataSource = GetTable("select work_order,factory_id from g_wo_base where rownum<=50");
            //設置下拉框數據源
            comboBox1.DataSource = GetTable("SELECT factory_id,factory_code FROM SYS_FACTORY");
            comboBox1.DisplayMember = "factory_code";
            comboBox1.ValueMember = "factory_id";
            comboBox1.Visible = false;
            //将下拉框嵌入到表格中
            dataGridView1.Controls.Add(comboBox1);
        }
        private void SelectIndexChange(object sender,EventArgs e)
        {
            //更改dataGridView中的值為下拉框所選的值
            ComboBox cmb = (ComboBox)sender;
            if (cmb == null) return;
            if (dataGridView1.CurrentCell.Value != cmb.SelectedValue)
                dataGridView1.CurrentCell.Value = cmb.SelectedValue;
        }
        private void dataGridView1_CurrentCellChanged(object sender, EventArgs e)
        {
            if (dataGridView1.CurrentCell == null) return; //點擊表頭(header)時，CurrentCell為null
            int row = dataGridView1.CurrentCell.RowIndex;
            int col = dataGridView1.CurrentCell.ColumnIndex;
            if (row != -1 && col ==1)
            {
                if (comboBox1.SelectedValue != dataGridView1.CurrentCell.Value)
                {
                    //在賦值前防止SelectedIndexChanged事件觸發產生錯誤
                    comboBox1.SelectedIndexChanged -= null;
                    comboBox1.SelectedValue = dataGridView1.CurrentCell.Value;
                    comboBox1.SelectedIndexChanged += SelectIndexChange;
                }
                //顯示下拉框
                Rectangle rec = dataGridView1.GetCellDisplayRectangle(col, row, true);
                comboBox1.Location = rec.Location;
                comboBox1.Size = rec.Size;
                comboBox1.Visible = true;
            }
            else
                comboBox1.Visible = false;
          
        }
    }