Question

我似乎无法让它发挥作用。我想用相同的数据填充多个下拉列表。每次运行相同的查询效率很低。这是我到目前为止所取得的成就：

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If (Not Page.IsPostBack) Then
        Dim ddlArray = {lst1, lst2, lst3, lst4, lst5, lst6, lst7, lst8, lst9, lst10}
        PopulateObjectList(ddlArray)
    End If
End Sub

Sub PopulateObjectList(ByVal ddlArray As Array)
    strSQL = "select distinct Object_ID, Object_Description from object"
    objCmd = New SqlCommand(strSQL, Master.DBConnect())

    For Each ddl In ddlArray
        ddl.DataSource = objCmd.ExecuteReader(CommandBehavior.CloseConnection)
        ddl.DataValueField = "Object_ID"
        ddl.DataTextField = "Object_Description"
        ddl.DataBind()
        ddl.Items.Insert(0, "Select Object")
    Next

    Call Master.DBDisconnect()
End Sub

这当然会给出错误：

ExecuteReader requires an open and available Connection. The connection's current state is closed.

因为在分配初始数据源后关闭了连接。我想我可以改为创建一个变量来保存数据，然后将其绑定到每个下拉列表，但数据集不起作用，我不确定如何做到这一点。

如何使用相同的数据填充十个下拉列表中的每一个，而无需在数据库上运行十个单独的查询？

Answer 1

  CommandBehavior.CloseConnection

首次使用后即关闭连接。相反，读取数据一次，将其复制到对象列表并绑定到该列表。

我想知道为什么DataSet不起作用。

Sub PopulateObjectList(ByVal ddlArray As Array)
strSQL = "select distinct Object_ID, Object_Description from object"

sqlCon = Master.DbConnect()

da = New SqlDataAdapter(strSQL, sqlCon)
ds = New DataSet

da.Fill(ds)

For Each ddl In ddlArray
    ddl.DataSource = ds
    ddl.DataValueField = "Object_ID"
    ddl.DataTextField = "Object_Description"
    ddl.DataBind()
    ddl.Items.Insert(0, "Select Object")
Next

Call Master.DBDisconnect()
End Sub

使用一个SQL查询填充多个下拉列表

1 个答案: