Question

OMG我已经这样做了两天，但仍然无法得到解决方案。这是我的情景：

我有三个组合框控件，我需要从数据集中加载数据。

cbCode1使用加载表单填充。
当cbCode1中选定的索引更改
当cbCode1中选定的索引更改

数据来自datset“description”和“id_code”中的两个字段。所以我想将描述的值与其id相关联。因为我需要稍后再问......

在加载表单中我有：

cbCode1.DataSource = D.Tables [0]; cbCode1.DisplayMember = D.Tables [0] .Columns [“description”]。ColumnName; cbCode1.ValueMember = D.Tables [0] .Columns [“id_code”]。ColumnName;

现在，来自cbcode1的选定索引发生变化：

private void cbCode1_SelectedIndexChanged(object sender, EventArgs e)
    {

        // Get dataset from DB
        DataSet D = new DataSet();
        D = reason_get(1, 1, 1); // IdStation, Active, Level

        // Ensure the cbcode2 is cleared
        cbCode2.Items.Clear();
        string SelectedValue = cbCode1.SelectedValue.ToString();

        foreach (DataRow row in D.Tables[0].Rows)
        {


            if (row["id_parent_code"].ToString () == SelectedValue ) 
            {

                cbCode2.DataSource = D.Tables[0];
                cbCode2.DisplayMember = D.Tables[0].Columns["description"].ColumnName;
                cbCode2.ValueMember = D.Tables[0].Columns["id_code"].ColumnName;

                cbCode2.SelectedIndex = 0;

            }
        }



    }

这段代码不起作用我不知道我做错了什么。请帮忙解决这个问题？

提前致谢！

新手程序员..

Answer 1

我之前没有这样做，但是我为datagridview做了类似的事情。您需要做的是使用actionlisteners。基本上填充第一个组合框，然后向其添加一个actionlistener，以便在所选索引更改时调用它。在该actionlistener中，它填充了第二个组合框。

Answer 2

尝试这样做，如下面的代码......

private void Form1_Load（object sender，EventArgs e） { FillCountry（）;

    }

    private void FillCountry()
    {
        string str = "SELECT CountryID, CountryName FROM Country";
        SqlCommand cmd = new SqlCommand(str,con);
        //cmd.Connection = con;
        //cmd.CommandType = CommandType.Text;
       // cmd.CommandText = "SELECT CountryID, CountryName FROM Country";
        DataSet objDs = new DataSet();
        SqlDataAdapter dAdapter = new SqlDataAdapter();
        dAdapter.SelectCommand = cmd;
        con.Open();
        dAdapter.Fill(objDs);
        con.Close();
        comboBox1.ValueMember = "CountryID";
        comboBox1.DisplayMember = "CountryName";
        comboBox1.DataSource = objDs.Tables[0];
    }

    private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (comboBox1.SelectedValue.ToString() != "")
        {
            int CountryID = Convert.ToInt32(comboBox1.SelectedValue.ToString());
            FillStates(CountryID);
            comboBox3.SelectedIndex = 0;
        }
    }

    private void FillStates(int countryID)
    {
        string str = "SELECT StateID, StateName FROM State WHERE CountryID =@CountryID";
        SqlCommand cmd = new SqlCommand(str, con);
       // SqlConnection con = new SqlConnection(Con);
       //  cmd.Connection = con;          
       // string str="SELECT StateID, StateName FROM State WHERE CountryID =@CountryID";
       // cmd.Connection = con;
        //cmd.CommandType = CommandType.Text;
       // cmd.CommandText = "SELECT StateID, StateName FROM State WHERE CountryID =@CountryID";
        cmd.Parameters.AddWithValue("@CountryID", countryID);
        DataSet objDs = new DataSet();
        SqlDataAdapter dAdapter = new SqlDataAdapter();
        dAdapter.SelectCommand = cmd;
        con.Open();
        dAdapter.Fill(objDs);
        con.Close();
        if (objDs.Tables[0].Rows.Count > 0)
        {
            comboBox2.ValueMember = "StateID";
            comboBox2.DisplayMember = "StateName";
            comboBox2.DataSource = objDs.Tables[0];
        }
    }

    private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
    {
        int StateID = Convert.ToInt32(comboBox2.SelectedValue.ToString());
        FillCities(StateID);
    }


    private void FillCities(int stateID)
    {
        //SqlConnection con = new SqlConnection(str,con);
        string str = "SELECT CityID, CityName FROM City WHERE StateID =@StateID";
        SqlCommand cmd = new SqlCommand(str,con);
       // cmd.Connection = con;
        //cmd.CommandType = CommandType.Text;
       // cmd.CommandText = "SELECT CityID, CityName FROM City WHERE StateID =@StateID";
        cmd.Parameters.AddWithValue("@StateID", stateID);
        DataSet objDs = new DataSet();
        SqlDataAdapter dAdapter = new SqlDataAdapter();
        dAdapter.SelectCommand = cmd;
        con.Open();
        dAdapter.Fill(objDs);
        con.Close();
        if (objDs.Tables[0].Rows.Count > 0)
        {
            comboBox3.DataSource = objDs.Tables[0];
            comboBox3.DisplayMember = "CityName"; 
            comboBox3.ValueMember = "CItyID";

        }

根据来自另一个组合框的所选索引填充组合框

2 个答案: