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我有一个带有 2 个列表框的表单。在这里，listbox1 填充了演员的姓名。如果从 listbox1 中选择了一个名称，则 listbox2 应该显示涉及该名称的电影的标题。如果选择了另一个名称，listbox2 将显示涉及该名称的电影的标题。

Call Connect()
    With Me
        STRSQL = "select mTitle from selectmovie where cName = '" & lstNames.SelectedItem & "'"
        Try
            myCmd.Connection = myConn
            myCmd.CommandText = STRSQL
            myReader = myCmd.ExecuteReader
            If (myReader.Read()) Then
                myReader.Close()
                myAdptr.SelectCommand = myCmd
                myAdptr.Fill(myDataTable)
                lstTitle.DisplayMember = "mTitle"
                lstTitle.ValueMember = "mTitle"

                If myDataTable.Rows.Count > 0 Then
                    For i As Integer = 0 To myDataTable.Rows.Count - 1
                        lstTitle.Items.Add(myDataTable.Rows(i)("mTitle"))
                    Next
                End If
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End With

没有错误。当我选择 1 项时，结果是正确的，但它留下了很多空间..这里是我的表单的屏幕截图：http: //www.flickr.com/photos/92925726@N06/8445945758/in/photostream/

当我选择actor3时输出变得更糟：http: //www.flickr.com/photos/92925726@N06/8445945724/in/photostream/

4

1 回答 1

1

Your main problem seems to be that you do not clear your lstTitle control before re-loading it with the new selection. Therefore, each time you select a new name, it will add all the titles for that name to the existing list of titles that are already loaded. Also, instead of using an integer to iterate all the indexes, it is easier to just use a For Each loop:

lstTitle.Items.Clear()
For Each row As DataRow In myDataTable.Rows
    lstTitle.Items.Add(row("mTitle"))
Next

However, I must also mention that you really should also be using a parameter in your query rather than dynamically building the SQL statement like that, for instance:

myCmd.CommandText = "select mTitle from selectmovie where cName = @name"
myCmd.Parameters.AddWithValue("name", lstNames.SelectedItem)

To select all the movies where all of the multiple selected actors are involved, you would need to add an additional condition to your where clause for each actor, for instance:

Dim builder As New StringBuilder()
builder.Append("select distinct mTitle from selectmovie where ")
For i As Integer = 0 to lstNames.SelectedItems.Count - 1
    Dim parameterName As String = "@name" & i.ToString()
    If i <> 0 Then
        builder.Append("and ")
    End If
    builder.Append(parameterName)
    builder.Append(" in (select cName from selectmovie where mTitle = m.mTitle) ")
    myCmd.Parameters.AddWithValue(parameterName, lstNames.SelectedItems(i))
Next
myCmd.CommandText = builder.ToString()
于 2013-02-04T21:17:50.963 回答