c#调用数据表的问题

Question

就是我用了一条语句       private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {...
         ...  （select * from score where studentnumber='" + comboBox1.Text + "'", myconn);
               ...
                 ...
score 表里有studentnumber,name，caursename,classname,score,
问怎样调用执行了此句sql语句后得到的一条结果。
在combox2-4里面显示出name，caursename，classname，score的值？

Answer 1

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e) 
{
  SqlConnection myconn = null;
  SqlDataReader = null;
  try
  {
    SqlConnection myconn = new SqlConnection("server=....");
    //确保studentnumber是varchar或char型的,否则去掉单引号
    string number = comboBox1.Text;
    string sql = "select name,caursename,classname,score from score where studentnumber='"+number+"'";
    SqlCommand cmd = new SqlCommandmyconn(sql,myconn);
    SqlDataReader reader = cmd.ExecuteReader();
    if(reader.HasRows)
    {
      combox2.Items.Clear(); //这种情况,三个都用广本框即可
      combox3.Items.Clear();
      combox4.Items.Clear();
      if(reader.Read())
      {
        combox2.Items.Add(reader.GetString(0));
        combox3.Items.Add(reader.GetString(1));
        combox4.Items.Add(reader.GetString(2));
      }
      combox2.SelectedIndex = 0;
      combox2.SelectedIndex = 0;
      combox2.SelectedIndex = 0;
    }
  }
  finaly
  {
    if(reader != null) reader.Close();
    if(myconn != null) myconn.Close();
  }
}

Answer 2

我做出来了，还是要谢谢你．^_^   
     private void comboBox3_SelectedIndexChanged(object sender, EventArgs e)
        {
            try
            {
                SqlConnection myconn = new SqlConnection();
                myconn.ConnectionString = "server=localhost;database=student2;uid=sa;pwd=123456;";
                myconn.Open();
                DataSet ds = new DataSet();
                SqlDataAdapter da = new SqlDataAdapter();
                da.SelectCommand = new SqlCommand("select * from score where studentnumber='" + comboBox3.Text + "'", myconn);
                da.Fill(ds, "student2");
                DataRow myDR = ds.Tables["student2"].Rows[0];
                string a = myDR["spename"].ToString();
                string b = myDR["classname"].ToString();
                
                    this.comboBox1.Text = a;
                    this.comboBox2.Text = b;
                    this.comboBox4.Text = myDR["coursename"].ToString();
                    this.comboBox5.Text = myDR["name"].ToString();
                    this.comboBox6.Text = myDR["semester"].ToString();
                    this.textBox1.Text = myDR["score"].ToString();
                
                
                     myconn.Close();
            }
            catch (SqlException ex)
            { MessageBox.Show(ex.ToString()); }