Question

显示ListView中显示的两个表中的数据的代码（CODE WORKS PERFECTLY）：

#Region "FillListView"
    Sub FillListview()
        LV.Items.Clear()
        myqry = "SELECT AccResult.StudNo,AccResult.CNumber,AccResult.FirstName,AccResult.LastName,AccResult.YrandSec,Exercises.Exer1,Exercises.Exer2,Exercises.Exer3,Exercises.Exer4,Exercises.Exer5 from AccResult INNER JOIN Exercises ON AccResult.StudNo = Exercises.StudNo ORDER BY AccResult.FirstName,AccResult.YrandSec Asc;"

        mycmd = New OleDbCommand(myqry, con)
        con.Open()
        mydr = mycmd.ExecuteReader
        While mydr.Read
            With LV
                .Items.Add(mydr("StudNo"))
                With .Items(.Items.Count - 1).SubItems
                    .Add(mydr("CNumber"))
                    .Add(mydr("FirstName"))
                    .Add(mydr("LastName"))
                    .Add(mydr("YrandSec"))
                    .Add(mydr("Exer1"))
                    .Add(mydr("Exer2"))
                    .Add(mydr("Exer3"))
                    .Add(mydr("Exer4"))
                    .Add(mydr("Exer5"))
                End With
            End With
        End While
        con.Close()
    End Sub
#End Region

填充ListView代码（错误）：

Public Sub PopulateListView()
        Me.LV.Items.Clear()
        Dim OleDr As OleDb.OleDbDataReader
        OleDr = OleDa.SelectCommand.ExecuteReader() <-----< ERROR: The specified field '[StudNo]' could refer to more than one table listed in the FROM clause of your SQL statement.

        Do While OleDr.Read()
            Dim Item As New ListViewItem
            Item.Text = IIf(OleDr.IsDBNull(0), "", OleDr.Item(0))

            For shtCntr = 1 To OleDr.FieldCount() - 1
                If Not OleDr.IsDBNull(shtCntr) Then
                    Item.SubItems.Add(OleDr.Item("CNumber"))
                    Item.SubItems.Add(OleDr.Item("FirstName"))
                    Item.SubItems.Add(OleDr.Item("LastName"))
                    Item.SubItems.Add(OleDr.Item("YrandSec"))
                    Item.SubItems.Add(OleDr.Item("Exer1"))
                    Item.SubItems.Add(OleDr.Item("Exer2"))
                    Item.SubItems.Add(OleDr.Item("Exer3"))
                    Item.SubItems.Add(OleDr.Item("Exer4"))
                    Item.SubItems.Add(OleDr.Item("Exer5"))
                Else
                    Item.SubItems.Add("")

                End If
            Next shtCntr
            Me.LV.Items.Add(Item)
        Loop
    End Sub

搜索代码：

Private Sub BSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BSearch.Click
        If txtSearch.Text = "" Then
               MsgBox("Please enter keyword to search...", MsgBoxStyle.Information, "Keyword to search...")
            txtSearch.Focus()
            Exit Sub
        End If
        Call OpenConnection()
         With OleDa
            Call Initialized()
            .SelectCommand = New OleDb.OleDbCommand()
            .SelectCommand.CommandText = "SELECT * FROM [AccResult],[Exercises] WHERE StudNo Like '%%" & txtSearch.Text & "%%' or [YrandSec] Like '%%" & txtSearch.Text & "%%' or [LastName] Like '%%" & txtSearch.Text & "%%'" & _
        "Or [FirstName] Like '%%" & txtSearch.Text & "%%' or [Exer1] Like '%%" & txtSearch.Text & "%%' or [Exer2] Like '%%" & txtSearch.Text & "%%' or [Exer3] Like '%%" & txtSearch.Text & "%%'" & _
        "Or [Exer4] Like '%%" & txtSearch.Text & "%%' or [Exer5] Like '%%" & txtSearch.Text & "%%' ORDER By YrandSec, LastName ASC"
            .SelectCommand.Connection = OleCn

            Call PopulateListView()

             If Me.LV.Items.Count >= 1 Then
                 MsgBox(Me.LV.Items.Count & " Record(s) found for " & "( " & Me.txtSearch.Text & " )", MsgBoxStyle.OkOnly, "Record(s) found...")
            Else
                 MsgBox("No record(s) found for " & "( " & Me.txtSearch.Text & " )" & " , please try again... ", MsgBoxStyle.Critical, "No record found...")
                txtSearch.Focus()
                  txtSearch.SelectAll()
            End If
        End With
        Call CloseConnection()

    End Sub

如何在两个数据表中搜索数据后填充listview。它在搜索后给我错误。提前谢谢。

Answer 1

似乎表AccResult和Exercises都包含一个名为StudNo的字段，当您在where语句中引用该字段时，数据库无法确定您引用的字段到。

要删除问题前缀，请在字段名StudNo前加上表格的名称，就像您在代码中所做的那样

说，请考虑使用字符串连接的查询注定要失败如果您的搜索字词中存在简单的单引号，则代码将失败并出现语法错误然后是Sql Injection的重大问题

With OleDa
    Dim searchTerm = "%" & txtSearch.Text & "%"
    Call Initialized()
    .SelectCommand = New OleDb.OleDbCommand()
    .SelectCommand.CommandText = "SELECT * FROM AccResult INNER JOIN Exercises " & _ 
                                 "ON AccResult.StudNo = Exercises.StudNo " & _
                                 "WHERE AccResult.StudNo Like ? " & _ 
                                 "or [YrandSec] Like ? " & _
                                 "or [LastName] Like ? " & _
                                 "Or [FirstName] Like ? " & _ 
                                 "or [Exer1] Like ? " & _
                                 "or [Exer2] Like ? " & _
                                 "or [Exer3] Like ? " & _
                                 "Or [Exer4] Like ? " & _
                                 "or [Exer5] Like ? " & _ 
                                 "ORDER By YrandSec, LastName ASC"
    .SelectCommand.Parameters.AddWithValue("@p1", searchTerm)
    .SelectCommand.Parameters.AddWithValue("@p2", searchTerm)
    .SelectCommand.Parameters.AddWithValue("@p3", searchTerm)
    .SelectCommand.Parameters.AddWithValue("@p4", searchTerm)
    .SelectCommand.Parameters.AddWithValue("@p5", searchTerm)
    .SelectCommand.Parameters.AddWithValue("@p6", searchTerm)
    .SelectCommand.Parameters.AddWithValue("@p7", searchTerm)
    .SelectCommand.Parameters.AddWithValue("@p8", searchTerm)
    .SelectCommand.Parameters.AddWithValue("@p9", searchTerm)
    .SelectCommand.Connection = OleCn
    .......

在这个版本中，我删除了丑陋的字符串连接并使用了参数化查询。该命令更具可读性，并且通配符char的连接只进行一次。不幸的是，OleDb无法通过名称识别参数，因此我们需要为查询文本中的每个占位符（@pX）添加参数（?）

在VB.Net中填充ListView

1 个答案: