如何從數據集填充下拉列表？

Question

我想用vb.net中的ASP下拉列表填充數據集中返回的存儲過程的結果。我想知道是否有人知道vb.net代碼來填充下拉列表？

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load 

    Dim connString As String = "Server=MYCOMPUTER\SQLEXPRESS;Database=scales;Trusted_Connection=True" 
    Dim myConn As New SqlConnection(connString) 
    myConn.Open() 
    Dim da As New SqlDataAdapter("select scaleName from scales", myConn) 
    Dim dt As New DataTable 
    da.Fill(dt) 

    ComboBox1.DisplayMember = "scaleName" 

    ComboBox1.DataSource = dt 
    myConn.Close() 

Answer 1

爲了顯示在DropDownList控件中的數據，可以使用下面的代碼。要使用存儲過程的結果，你需要創建SELECT命令：

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load 
    If Not Page.IsPostBack Then 
     Dim dt As New DataTable 
     Dim connString As String = "Server=MYCOMPUTER\SQLEXPRESS;Database=scales;Trusted_Connection=True" 
     Using myConn As New SqlConnection(connString) 
      myConn.Open() 
      Using cmd = myConn.CreateCommand() 
       cmd.CommandType = CommandType.StoredProcedure 
       cmd.CommandText = "dbo.uspMyStoredProc" 
       cmd.Parameters.AddWithValue("@MyInputParam", 123) 
       Using da As New SqlDataAdapter(cmd) 
        da.Fill(dt) 
       End Using 
      End Using 
     End Using 
     ComboBox1.DisplayMember = "scaleName" 
     ComboBox1.DataSource = dt 
     ComboBox1.DataBind() 
    End If 
    ' ... 
End Sub 

我調整了以下幾件事：

• 通常只需要綁定數據的初始請求。因此，開頭的if語句將檢查IsPostBack屬性。
• 爲了可靠地關閉和部署連接和數據數據集，我添加了一些using語句。
• 爲了訪問存儲過程，我創建了一個SqlCommand並將CommandType設置爲StoredProcedure。 CommandText被設置爲存儲過程的名稱。在示例中，我還添加了一個名爲MyInputParam的參數，該參數被髮送到存儲過程。

Answer 2

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load 
      IF Not IsPostback then 
       PopulateDropdown() 
      End IF 
End Sub 

Private Sub PopulateDropDown() 
     Dim connString As String = "Server=MYCOMPUTER\SQLEXPRESS;Database=scales;Trusted_Connection=True" 
     Dim myConn As New SqlConnection(connString) 
     myConn.Open() 
     Dim da As New SqlDataAdapter("select ScaleId, scaleName from scales", myConn) 
     Dim dt As New DataTable 
     da.Fill(dt) 

      Me.ComboBox1.DataTextField = "scaleName " 
      Me.ComboBox1.DataValueField = "ScaleId" 
      Me.ComboBox1.DataSource = dt 
      Me.ComboBox1.DataSourceID = String.Empty 
      Me.ComboBox1.DataBind() 

    myConn.Close() 
End Sub