C# 如何获取selectedindex并进行sql查询

Question

我试图获取列表框 1 和 2 的 selectedindex 并根据两个列表框中选择的值更新我的数据库表，但找不到将 selectedindexes 获取到我的 sql 语句中的方法。有什么建议么？

     private void Form1_Load(object sender, EventArgs e)
     {
        String cs = "Database=something;User=-;Password=-";
        MySqlConnection dbconn = new MySqlConnection(cs);
        dbconn.Open();

        DataSet ds = new DataSet();
        MySqlDataAdapter adapter = new MySqlDataAdapter(
            "select * from reservasjon WHERE Rom_nr IS NULL ", dbconn);
        adapter.Fill(ds);
        this.listBox1.DataSource = ds.Tables[0];
        this.listBox1.DisplayMember = "Rnr";
      }

    private void button1_Click(object sender, EventArgs e)
    {
        String cs = "Database=something;User=-;Password=-";
        MySqlConnection dbconn = new MySqlConnection(cs);
        dbconn.Open();
        DataSet ds2 = new DataSet();
        MySqlDataAdapter adapter2 = new MySqlDataAdapter(
           "select * from rom WHERE etasje = '1' AND opptatt='1'", dbconn);
        adapter2.Fill(ds2);
        this.listBox2.DataSource = ds2.Tables[0];
        this.listBox2.DisplayMember = "Rom_nr";
    }

    private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string value1 = listBox1.SelectedIndex.ToString();
    }

    private void listBox2_SelectedIndexChanged(object sender, EventArgs e)
    {
        string value2 = listBox2.SelectedIndex.ToString();
    }



    private void button4_Click(object sender, EventArgs e)
    {
        string value1 = listBox2.Text;
        string value2 = listBox1.Text;

        MySqlDataReader dr = null;

        try
        {
            String cs = "Database=something;User=-;Password=-";
            string selectStatement = "UPDATE reservasjon SET Rom_nr='102' WHERE Rnr='2';";
            System.Data.DataTable dt = new System.Data.DataTable();
            MySqlConnection dbconn = new MySqlConnection(cs);
            dbconn.Open();
            MySqlDataAdapter sqlDa = new MySqlDataAdapter();
            sqlDa.SelectCommand = new MySqlCommand(selectStatement, dbconn);
            MySqlCommandBuilder cb = new MySqlCommandBuilder(sqlDa);
            sqlDa.Fill(dt);
            dt.Rows[0]["Rnr"] = "";
            sqlDa.UpdateCommand = cb.GetUpdateCommand();
            sqlDa.Update(dt);
        }

        catch (Exception s)
        {
            Console.WriteLine(s.Message);
        }
    }

Answer 1

这应该可以解决问题:

   private void button4_Click(object sender, EventArgs e)
    {
        string value1 = listBox2.Text;
        string value2 = listBox1.Text;

        MySqlDataReader dr = null;

        try
        {
            String cs = "Database=something;User=-;Password=-";
            string selectStatement = "UPDATE reservasjon SET Rom_nr='"+value2+"' WHERE Rnr='"value1+"';";
            System.Data.DataTable dt = new System.Data.DataTable();
            MySqlConnection dbconn = new MySqlConnection(cs);
            dbconn.Open();
            MySqlDataAdapter sqlDa = new MySqlDataAdapter();
            sqlDa.SelectCommand = new MySqlCommand(selectStatement, dbconn);
            MySqlCommandBuilder cb = new MySqlCommandBuilder(sqlDa);
            sqlDa.Fill(dt);
            dt.Rows[0]["Rnr"] = "";
            sqlDa.UpdateCommand = cb.GetUpdateCommand();
            sqlDa.Update(dt);
        }

        catch (Exception s)
        {
            Console.WriteLine(s.Message);
        }
    }