Datenbankinformationen mithilfe von DropDownList dynamisch in Label abrufen

Question

Ich versuche, Daten dynamisch in Labels abzurufen. Das bedeutet, dass sich die Beschriftung ändert, wenn ich das DropDownList-Element auswähle. Ist es möglich?

aspx:

<asp:DropDownList ID="ddl_CNo" AutoPostBack="true" runat="server" Height="16px" Width="138px" OnSelectedIndexChanged="ddl_CNo_SelectedIndexChanged" > 
       </asp:DropDownList> 

aspx.cs:

//page load box retrieve 
    SqlConnection myConnect2 = new SqlConnection(_connStr); 
    string strCommandText2 = "SELECT Card_Type, Card_Type2, Card_Number, Card_Number2, Name_On_Card, Name_On_Card2, Expired_Date, Expired_Date2 From Card_Details where Card_Id = @Card_Id"; 
    myConnect2.Open(); 
    SqlCommand cmd2 = new SqlCommand(strCommandText2, myConnect2); 
    cmd2.Parameters.AddWithValue("@Card_Id", 1); 

    ////open connection and retrieve data by calling ExecuteReader 

    SqlDataReader dr2 = cmd2.ExecuteReader(); 

    if (dr2.Read()) 
    { 

     string CNo1 = dr2["Card_Number"].ToString(); 
     string CNo2 = dr2["Card_Number2"].ToString(); 

     CNo = new List<string>(); 
     CNo.Add(dr2["Card_Number"].ToString()); 
     CNo.Add(dr2["Card_Number2"].ToString()); 

     ddl_CNo.DataSource = CNo; 
     ddl_CNo.DataBind(); 

    ddl_CNo.Text = dr2["Card_Number"].ToString(); 
    ddl_CNo.Text = dr2["Card_Number2"].ToString(); 
    Lbl_CardName.Text = dr2["Name_On_Card"].ToString(); 
    Lbl_CardName.Text = dr2["Name_On_Card2"].ToString(); 
    Lbl_CardType.Text = dr2["Card_Type"].ToString(); 
    Lbl_CardType.Text = dr2["Card_Type2"].ToString(); 
    Lbl_EDate.Text = dr2["Expired_Date"].ToString(); 
    Lbl_EDate.Text = dr2["Expired_Date2"].ToString(); 


    } 
    dr2.Dispose(); 
    dr2.Close(); 

    myConnect2.Close(); 

    if (!IsPostBack) 
    { 

     LoadCart(); 

    } 
} 

DDLSelectedIndexChanged:

protected void ddl_CNo_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    { 
     SqlConnection myConnect2 = new SqlConnection(_connStr); 
     string strCommandText2 = "SELECT Card_Type, Card_Type2, Card_Number, Card_Number2, Name_On_Card, Name_On_Card2, Expired_Date, Expired_Date2 From Card_Details where Card_Id = @Card_Id"; 
     myConnect2.Open(); 
     SqlCommand cmd2 = new SqlCommand(strCommandText2, myConnect2); 
     cmd2.Parameters.AddWithValue("@Card_Id", 1); 
     SqlDataReader dr2 = cmd2.ExecuteReader(); 

     if (dr2.Read()) 
     { 

      string CNo1 = dr2["Card_Number"].ToString(); 
      string CNo2 = dr2["Card_Number2"].ToString(); 

      CNo = new List<string>(); 
      CNo.Add(dr2["Card_Number"].ToString()); 
      CNo.Add(dr2["Card_Number2"].ToString()); 

      ddl_CNo.DataSource = CNo; 
      ddl_CNo.DataBind(); 

      if (ddl_CNo.SelectedItem.Equals("Card_Number")) 
      { 
       Lbl_CardName.Text = dr2["Name_On_Card"].ToString(); 
       Lbl_CardType.Text = dr2["Card_Type"].ToString(); 
       Lbl_EDate.Text = dr2["Expired_Date"].ToString(); 
      } 
      else if (ddl_CNo.SelectedItem.Equals("Card_Number2")) 
      { 
       Lbl_CardName.Text = dr2["Name_On_Card2"].ToString(); 
       Lbl_CardType.Text = dr2["Card_Type2"].ToString(); 
       Lbl_EDate.Text = dr2["Expired_Date2"].ToString(); 
      } 
      dr2.Dispose(); 
      dr2.Close(); 

      myConnect2.Close(); 
     } 
    } 
} 

Bild als Referenz:

Ich bin wirklich neu für alle diese, jede Hilfe wird sehr geschätzt :)

Answer 1

Nach Berücksichtigung Ihres Szenarios dachte ich, es wird die Lösung sein, die funktioniert. Binden Sie Ihre DropDownList einmal innerhalb von Seitenladen und dann onselcedIndexChanged können wir die Daten auf der Grundlage der ausgewählten CardID abrufen und mit allen Etiketten, die Daten benötigen, binden. Sie können den Code gemäß Ihrer Spezifikation optimieren. Versuchen Sie es einmal:

string _connStr =ConfigurationManager.ConnectionStrings[""].ConnectionString; 
     string query = ""; 
     protected void Page_Load(object sender, EventArgs e) 
     { 
      if (!IsPostBack) 
      { 
       query = "SELECT Card_ID,Card_Name From Card_Details"; // Do Change your query according to your requirment 
       DataTable drpdt = SelectedBindValue(query); 
       if (drpdt.Rows.Count > 0) 
       { 
        drp.DataSource = drpdt; 
        drp.DataTextField = "Card_Name"; 
        drp.DataValueField = "Card_ID"; 
        drp.DataBind(); 
       } 
      } 
     } 

     protected void Unnamed_SelectedIndexChanged(object sender, EventArgs e) 
     { 
      string cardId = drp.SelectedValue; 
      query = String.Format("SELECT Card_Type, Card_Type2, Card_Number, Card_Number2, Name_On_Card, Name_On_Card2, Expired_Date, Expired_Date2 From Card_Details where Card_Id = {0}",cardId); 
      DataTable lablebind = SelectedBindValue(query); 
      if (lablebind.Rows.Count>0) 
      { 
       Lbl_CardName.Text = lablebind.Rows[0]["Name_On_Card"].ToString(); // considering there is only one row 
       Lbl_CardType.Text = lablebind.Rows[0]["Card_Type"].ToString();// considering there is only one row 
       Lbl_EDate.Text = lablebind.Rows[0]["Expired_Date"].ToString();// considering there is only one row 
      } 
     } 
     protected DataTable SelectedBindValue(string query) 
     { 
      using(SqlConnection myConnect2 = new SqlConnection(_connStr)) 
      {    
       using(SqlDataAdapter sqd = new SqlDataAdapter(query,myConnect2)) 
       { 
        using (DataTable dt = new DataTable()) 
        { 
         sqd.Fill(dt); 
         return dt; 
        } 
       } 
      } 
     }