如何插入Databinded组合框 [英] How Do I Insert Into A Databinded Combo Box

问题描述

如何在数据结构组合框的索引零中插入新行，这是我的代码，但它似乎不起作用。

 使用（SqlCommand command =  new  SqlCommand（ 从base_user_details中选择firstname，strCon））
 {
 command.CommandType = CommandType.Text; 
  //   command.Parameters.Add（@ SelectOption，SqlDbType.VarChar，25）.Value = staffFirstname;  
  //   command.Parameters.Add（@ firstname，SqlDbType .VarChar，50）。Value = txtSearch.Text.Trim（）;  
 使用（SqlDataAdapter adapter =  new  SqlDataAdapter（command））
 {
  using （dt =  new  DataSet（））
 {
 adapter.Fill（dt）; 
 cboSchools.DataSource = dt.Tables [ 0 ]; 
 cboSchools.ValueMember =   firstname; 
 cboSchools.DisplayMember =   firstname; 
 
 cboSchools.Items.Insert（ 0 ，  ---选择---）; 
} 
} 
} 

解决方案

首先创建一个类，如

  public   class  ComboboxItem 
 {
  public   string 文字{获得;  set ; } 
  public   object 值{ get ;  set ; } 
 
  public  覆盖  string  ToString（）
 {
  return 文字; 
} 
} 

添加代码以使用此类您想要添加项目

 ComboboxItem item =  new  ComboboxItem（）; 
 item.Text =   Item text1; 
 item.Value =  12 ; 
 comboBox1.Items.Insert（ 0 ，item）; 

试试这样：

 使用（dt =  new  DataSet（））
 {
 adapter.Fill（dt）; 
 cboSchools.DataSource = dt.Tables [ 0 ]; 
 cboSchools.ValueMember =   firstname; 
 cboSchools.DisplayMember =   firstname; 
 
 cboSchools.Items.Add（  ---选择---， 0 ）; 
} 

在设置数据源添加行到数据表之前执行以下操作

 adapter.Fill（DT）; 
 DataRow row = dt.Tables [ 0 ]。NewRow（）; 
 row.ItemArray =  new   object  [] {   -  select  - ）; 
 dt.Tables [ 0 ]。Rows.InsertAt（row， 0 ）; 
 cboSchools.DataSource = dt.Tables [ 0 ]; 
 cboSchools.ValueMember =   firstname; 
 cboSchools.DisplayMember =   firstname; 

How do i insert new row into index zero of a databinded combo box, here is my code, but it doesn't seem to work.

using ( SqlCommand command = new SqlCommand( "Select firstname from base_user_details", strCon ) )
                    {
                        command.CommandType = CommandType.Text;
                        //command.Parameters.Add( "@SelectOption", SqlDbType.VarChar, 25 ).Value = "staffFirstname";
                        //command.Parameters.Add( "@firstname", SqlDbType.VarChar, 50 ).Value = txtSearch.Text.Trim( );
                        using ( SqlDataAdapter adapter = new SqlDataAdapter( command ) )
                        {
                            using ( dt = new DataSet( ) )
                            {
                                adapter.Fill( dt );
                                cboSchools.DataSource = dt.Tables[0];
                                cboSchools.ValueMember="firstname";
                                cboSchools.DisplayMember ="firstname";
                                
                                cboSchools.Items.Insert( 0, "  ---Select---" );
                            }
                        }
                    }

解决方案

first create one class like

public class ComboboxItem
{
    public string Text { get; set; }
    public object Value { get; set; }

    public override string ToString()
    {
        return Text;
    }
}

add code to use this class where you want to add item

ComboboxItem item = new ComboboxItem();
item.Text = "Item text1";
item.Value = 12;
comboBox1.Items.Insert(0,item);

Try like this :

using ( dt = new DataSet( ) )
                            {
                                adapter.Fill( dt );
                                cboSchools.DataSource = dt.Tables[0];
                                cboSchools.ValueMember="firstname";
                                cboSchools.DisplayMember ="firstname";
                                
                                cboSchools.Items.Add("---Select---",0 );
                            }

do as below, before set the data source add row to datatable

adapter.Fill(dt);
DataRow row = dt.Tables[0].NewRow();
row.ItemArray = new object[] { "--select--");
dt.Tables[0].Rows.InsertAt(row, 0);
cboSchools.DataSource = dt.Tables[0];
cboSchools.ValueMember="firstname";
cboSchools.DisplayMember ="firstname";

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