Question

我是视觉基础的新手。我想根据电话号码删除记录。程序将要求用户输入他的号码，并在将电话号码与数据库匹配后删除记录。我试过这样做，但是它给了我一个错误＆＃34;在标准表达式中键入不匹配＆＃34;。我正在使用ms access 2007并且我已经将电话列的数据类型设置为Number。这是我的vb代码。请帮我。这一定是我愚蠢的错误之一。在插入数据模块中，我已将数据类型指定为Long，在此之前我已将其指定为Integer但仍存在相同的错误。

Imports System.Data.OleDb
Public Class Form5
    Public Connstring As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source = C:\Users\AMEN\Documents\Railway.accdb"
    Public Conn As New OleDbConnection

    Private Sub Form5_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Conn.ConnectionString = Connstring
        If Conn.State = ConnectionState.Closed Then
            Conn.Open()
        End If

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim okToDelete As MsgBoxResult = MsgBox("Are you sure you want to cancel your ticket?", MsgBoxStyle.YesNo)

        If okToDelete = MsgBoxResult.Yes Then
            Dim str As String
            str = "Delete from Table2 Where Phone = '" & TextBox1.Text & "'"
            Dim cmd As OleDbCommand = New OleDbCommand(str, Conn)
            Try
                cmd.ExecuteNonQuery()
                cmd.Dispose()
                Conn.Close()

                MsgBox("Your Ticket Cancelled Sucessfully ! ")
            Catch ex As Exception
                MsgBox(ex.Message)
            End Try
        ElseIf okToDelete = MsgBoxResult.No Then
        End If

    End Sub
End Class

Answer 1

电话号码应存储为字符串而不是数字。但是，如果您的电话字段是数字，那么您的查询中的一部分是错误的在这种情况下，TextBox1.Text周围不需要引号。这会将您的输入视为字符串，并且此字符串不能用于在数字字段中搜索。

最好的方法是使用参数化查询，您可以在其中指定传递的参数的数据类型（我假设你已经在Access中创建了电话号码作为长号号码）

If okToDelete = MsgBoxResult.Yes Then

    ' Check if your user types really a number.
    Dim number As Integer
    if Not Int32.TryParse(TextBox1.Text, number) Then
        MessageBox.Show("Not a valid number!")
        return
    End If
    Dim str As String
    str = "Delete from Table2 Where Phone = @phone"
    Dim cmd As OleDbCommand = New OleDbCommand(str, Conn)
    Try
        cmd.Parameters.Add("@phone", OleDbType.Integer).Value = number
        cmd.ExecuteNonQuery()
        ....

在条件表达式中键入不匹配

1 个答案: