如何从数据集填充下拉列表？

Question

我想用vb.net中的ASP下拉列表填充数据集中返回的存储过程的结果。我想知道是否有人知道vb.net代码来填充下拉列表？

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

为了显示在DropDownList控件中的数据，可以使用下面的代码。要使用存储过程的结果，你需要创建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 

我调整了以下几件事：

• 通常只需要绑定数据的初始请求。因此，开头的if语句将检查IsPostBack属性。
• 为了可靠地关闭和部署连接和数据数据集，我添加了一些using语句。
• 为了访问存储过程，我创建了一个SqlCommand并将CommandType设置为StoredProcedure。 CommandText被设置为存储过程的名称。在示例中，我还添加了一个名为MyInputParam的参数，该参数被发送到存储过程。

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