Question

我有两个组合框。我在第一个组合框中插入一个值，现在我希望我的第二个组合框根据第一个组合框更新其值。我该怎么做？

Answer 1

处理第一个ComboBox的{{3}}事件，然后根据第一个ComboBox的{{3}}值更新第二个组合框。

一个快速示例（检索SelectedItem时没有错误处理）：

public partial class Form1 : Form
{
    private string[] comboBox1Range = new[] { "A", "B", "C", "D" };
    private string[] comboBox2RangeA = new[] { "A1", "A2", "A3", "A4" };
    private string[] comboBox2RangeB = new[] { "B1", "B2", "B3", "B4" };
    private string[] comboBox2RangeC = new[] { "C1", "C2", "C3", "C4" };
    private string[] comboBox2RangeD = new[] { "D1", "D2", "D3", "D4" };

    public Form1()
    {
        InitializeComponent();
        comboBox1.SelectedIndexChanged += comboBox1_SelectedIndexChanged;
        comboBox1.Items.AddRange(comboBox1Range);
    }

    private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string selectedValue = comboBox1.SelectedItem as string;

        switch (selectedValue)
        {
            case "A":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeA);
                break;
            case "B":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeB);
                break;
            case "C":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeC);
                break;
            case "D":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeD);
                break;
        }
    }
}

Answer 2

订阅第一个组合框的值更改事件并填充第二个：

combobox1.SelectedIndexChanged+= new EventHandler(ListBox1_SelectedIndexChanged);

private combobox1_SelectedIndexChanged(object sender, EventArgs e)
{
    // do stuff with combobox2
}

或

combobox1.SelectedValueChanged += new EventHandler(ListBox1_SelectedValueChanged);

private combobox1_SelectedValueChanged(object sender, EventArgs e)
{
    // do stuff with combobox2
}

人口：

combobox2.Items.Add(new object());
combobox2.Items.Add(new ListItem("caption", "value"));
// etc

查找现有项目：

var index = combobox2.FindStringExact(combobox1.SelectedText);
if (index != -1)
    comobox2.SelectedItem = combobox2.Items[index];

Answer 3

代码示例，带有两个组合框的Winform数据绑定到数据集中的两个表。表“lstCountries”当前国家/地区列表表所有国家/地区的所有州/省的“lstState”列表。

表lstCountries（Int32 CountryID，string CountryName）表lstStates（Int32 StateID，Int32 CountryID，string StateName）

在这段代码中，我填充了基于值选择的cboCountry的cboState 两个combodropdown都绑定到从数据库中提取的数据表。

//  Load data from database (not shown)
// _dataSet.Tables["lstCountries"] datasource for cboCountry
// _dataSet.Tables["lstStates"] datasource for cboState
//  
// cboCountry - comboDropDown - List on countries 
// cboState  = comboDropDown  - List of states

// Use boolean bloading to prevent setting datasource for cboState when cboCountry is intially loaded.

    void cboCountry_SelectedIndexChanged(object sender, EventArgs e)
    {
        ComboBox cbo = (sender as ComboBox);
        if (cbo.SelectedIndex > -1 && !bloading)
        {
            Int32 countryID = Convert.ToInt32(((System.Data.DataRowView)(cbo.SelectedItem)).Row.ItemArray[0].ToString());

            cboState.Text = "";
            DataView view = _dataSet.Tables["lstStates"].DefaultView;
            view.RowFilter = string.Format("CountryID={0}", countryID);
            DataTable table = view.ToTable();
            cboState.DataSource = table;
            cboState.SelectedIndex = -1;
    }

Answer 4

我想选择Ders this cmbDers然后cmbKonu更新相关的SQL，就像Country-City一样。但是我得到的数据类型不匹配。什么问题？

表单加载 OleDbDataAdapter adp = new OleDbDataAdapter（“select * from Ders”，baglanti）; DataTable dt = new DataTable（）; baglanti.Open（）; adp.Fill（DT）; cmbDers.DataSource = dt; cmbDers.DisplayMember =“DersAd”; cmbDers.ValueMember =“DersID”; baglanti.Close（）;

private void cmbDers_SelectedIndexChanged(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    OleDbDataAdapter adp = new OleDbDataAdapter ("select * from Konu where DersID = '" +cmbDers.SelectedItem+"'",baglanti);   
    adp.Fill(dt);
    cmbKonu.DataSource = dt;
    cmbKonu.DisplayMember = "KonuAd";
    cmbKonu.ValueMem`enter code here`ber = "KonuID";
    baglanti.Close();`enter code here`

当第一个组合框获得某个值时自动更新组合框

4 个答案: