通過sql select語句顯示ID和名稱

Question

• 我有2個下拉列表，1個標籤& 1個文本框。

• 選擇「產品類別」@ 1st ddl，2nd ddl顯示所有產品類別。

• 問題是，我怎麼可能顯示產品類別id @標籤，並在加載/選擇第二個ddl時顯示文本框名稱？

• 我有以下代碼：

 

Public Sub FilterProductCategory() 
    Dim myConn As New SqlConnection 
    Dim myCmd As New SqlCommand 
    Dim dtrReader As SqlDataReader 


    myConn.ConnectionString = ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString 
    myCmd = myConn.CreateCommand 
    myCmd.CommandText = "SELECT product_category_id, product_category_name FROM ProductCategory ORDER BY product_category_name" 

    Try 
     myConn.Open() 
     dtrReader = myCmd.ExecuteReader() 

     If dtrReader.HasRows Then 
      DropDownList2.Items.Clear() 
      DropDownList2.DataSource = dtrReader 
      DropDownList2.DataValueField = "product_category_name" 
      DropDownList2.DataBind() 
     End If 
     dtrReader.Close() 
     myConn.Close() 
    Catch 
    End Try 
End Sub 

Answer 1

剛剛成立的：

DropDownList2.DataTextField = "product_category_name" 
DropDownList2.DataValueField = "product_category_id" 

所以當你嘗試dropdownlist2.selectedvalue那麼你將得到ID，當ü嘗試dropdownlist2.selecteditem.text那麼它會給你的產品類別名稱..

希望它會解決你的問題

Answer 2

希望這有助於，聽起來很簡單。我假設您的標籤和文本框的ID與下拉列表的格式相同。如果不是，請替換您自己的ID。此代碼也完全運行在服務器端，這意味着您將刷新整個頁面來完成這個相當簡單的任務。如果這不是問題，那麼通過一切手段使用這種方法，否則我會建議在客戶端使用JavaScript來做到這一點。

Protected Sub DropDownList2_SelectedIndexChanged(Sender as Object, e as EventArgs) Handles DropDownList2.SelectedIndexChanged 
Label1.Text = DropDownList2.SelectedValue 
TextBox1.Text = DropDownList2.SelectedItem.Text 
End Sub 

Answer 3

首套DataTextField到您的下拉列表display text（類別名稱）和DataValueField到您的下拉列表SelectedValue（categoryID）。

DropDownList2.DataTextField = "product_category_name"; 
DropDownList2.DataValueField = "product_category_id"; 

和DropDownList中的SelectIndexChanged Event使用SelectedValue屬性來訪問category ID AMD SelectedItem.Text訪問Categoryname

Protected Sub DropDownList2_SelectedIndexChanged(Sender as Object, e as EventArgs) Handles DropDownList2.SelectedIndexChanged 
Label1.Text = DropDownList2.SelectedValue 
TextBox1.Text = DropDownList2.SelectedItem.Text 
End Sub 

檢查DropDownList Class有關這些屬性的信息等。

檢查這個例子：

protected void Page_Load(object sender, EventArgs e) 
     { 
      if (!IsPostBack) 
      { 
       BindList(); 
      } 
     } 

     private void BindList() 
     { 
      SqlConnection con = new SqlConnection("server=.\\sqlexpress;initial catalog=test;integrated security=true;"); 
      SqlDataReader reader; 
      SqlCommand command = con.CreateCommand(); 
      command.CommandText = "Select * from UserTable order by UserName"; 
      try 
      { 
       con.Open(); 
       reader = command.ExecuteReader(); 
       if (reader.HasRows) 
       { 
        DropDownList1.DataSource = reader; 
        DropDownList1.DataValueField = "userid"; 
        DropDownList1.DataTextField = "UserName"; 
        DropDownList1.DataBind(); 
       } 

       reader.Close(); 
       con.Close(); 
      } 
      catch (Exception) 
      { 
       throw; 
      } 
     } 

     protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e) 
     { 
      Label1.Text = DropDownList1.SelectedValue; 
      TextBox1.Text = DropDownList1.SelectedItem.Text; 
     } 

輸出///