C# 当第一个组合框获得某些值时,自动更新组合框
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值更新它的值。我应该怎么做?订阅第一个组合框的值更改事件并填充第二个:C# 当第一个组合框获得某些值时,自动更新组合框,c#,winforms,combobox,C#,Winforms,Combobox,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值更新它的值。我应该怎么做?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
combobox1.SelectedIndexChanged+= new EventHandler(ListBox1_SelectedIndexChanged);
private combobox1_SelectedIndexChanged(object sender, EventArgs e)
{
// do stuff with combobox2
}
或
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];
处理第一个组合框的事件,然后根据第一个组合框的值更新第二个组合框
一个快速示例(检索SelectedItem时的SAN错误处理):
代码示例,Winform带有两个组合框,数据绑定到数据集中的两个表。 表“最不发达国家”当前国家名单 表“州”列出了所有国家的所有州/省 表1国家(Int32 CountryID,字符串CountryName) 表LSTATES(Int32 StateID、Int32 CountryID、字符串StateName) 在这段代码中,我根据选择的值cbocontry填充cboState 而这两个下拉列表都绑定到从数据库获取的数据表
// 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;
}
我想选择这个cmbDers,然后选择cmbKonu更新相关的SQL,就像那个国家/城市一样。但我得到一个数据类型不匹配。问题是什么 模板荷载 OleDbDataAdapter adp=新的OleDbDataAdapter(“从Ders中选择*”,baglanti); DataTable dt=新的DataTable(); baglanti.Open(); 自动进料(dt); cmbDers.DataSource=dt; cmbDers.DisplayMember=“DersAd”; cmbDers.ValueMember=“DersID”; baglanti.Close()
你在使用哪种技术?WPF、Silverlight、winforms?填充第二个的语法是什么?我需要这样做,当第一个组合框得到一个值“a”时,例如,第二个组合框应该在组合框的下拉列表中自动显示最后一个值。我无法获取更新第二个组合框的值的语法。我的第二个组合框中已经有项目,我只想在我的第一个组合框获得某个值时显示最后一个项目。我不需要在第二个组合框中添加任何内容。@ghd:不客气!别忘了接受其中一个答案)
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;
}
}
}
// 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;
}
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`