从 Microsoft Access 数据库更新组合框中的项目

问题描述

我正在 VB.NET 中制作家具租赁系统以更新 ComboBox 数据库中的 Microsoft Access。此更新 ComboBox 的代码不起作用；它仅适用于一项，对于其他项目则显示“未找到记录”。

我的数据库使用 Microsoft Access。

Public Class Form8
    Dim cn As New OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\jeeva\Desktop\VB Project\18HU5A1015.accdb")
    Private Sub update_Load(sender As Object,e As EventArgs) Handles MyBase.Load
        cn.open()
        Dim cm As New OleDb.OleDbCommand("select * from customerinfo",cn)
        Dim dr As OleDb.OleDbDataReader = cm.ExecuteReader
        While dr.Read
            ComboBox1.Items.Add(dr(0).ToString)
            ComboBox2.Items.Add(dr(1).ToString)
            ComboBox3.Items.Add(dr(2).ToString)
            ComboBox4.Items.Add(dr(3).ToString)
        End While
        dr.Close()
        cn.Close()
    End Sub

    Private Sub Button1_Click(sender As Object,e As EventArgs) Handles Button1.Click
        Dim customername = TextBox1.Text
        Dim customerid = TextBox2.Text
        Dim customeraddress = TextBox3.Text
        Dim customeraadharno = TextBox4.Text
        Try
            cn.open()
            Dim cmd As New OleDb.OleDbCommand()
            cmd.CommandText = "Update customerinfo set customername='" + customername + "' where customername='" + ComboBox1.SelectedItem() + "'"
            cmd.CommandText = "Update customerinfo set customerid='" + customerid + "' where customername='" + ComboBox2.SelectedItem() + "'"
            cmd.CommandText = "Update customerinfo set customeraddress='" + customeraddress + "' where customername='" + ComboBox3.SelectedItem() + "'"
            cmd.CommandText = "Update customerinfo set customeraadharno='" + customeraadharno + "' where customername='" + ComboBox4.SelectedItem() + "'"
            cmd.Connection = cn

            Dim i = cmd.ExecuteNonQuery
            If i > 0 Then
                MsgBox("Record is updated successfully")
            Else
                MsgBox("No record found")
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        Finally
            cn.Close()
        End Try
    End Sub

    Private Sub Button1_Click_1(sender As Object,e As EventArgs) Handles Button1.Click

    End Sub

解决方法

不要更改customerid，需要使用唯一的customerid 来更新表。 看看下面的例子：

Dim cn As New OleDb.OleDbConnection("Provider=...;")
Private Sub Form1_Load(sender As Object,e As EventArgs) Handles MyBase.Load
    cn.Open()
    Dim adapter As New OleDb.OleDbDataAdapter("select customerid,customername from customerinfo",cn)
    Dim dt As DataTable = New DataTable
    adapter.Fill(dt)
    ComboBox1.DataSource = dt
    ComboBox1.DisplayMember = "customername"
    ComboBox1.ValueMember = "customerid"
    cn.Close()

End Sub

Private Sub Button1_Click(sender As Object,e As EventArgs) Handles Button1.Click
    Try

        Dim cmd As New OleDb.OleDbCommand()
        cmd.Connection = cn

        cmd.CommandText = "Update customerinfo set customername = @customername,customeraddress = @customeraddress,customeraadharno = @aadharno where customerid=@customerid"
        cmd.Parameters.AddWithValue("customername",TextBox1.Text)
        cmd.Parameters.AddWithValue("customeraddress",TextBox2.Text)
        cmd.Parameters.AddWithValue("aadharno",TextBox3.Text)
        cmd.Parameters.AddWithValue("customerid",ComboBox1.SelectedValue)
        cn.Open()
        cmd.ExecuteNonQuery()
        MsgBox("Successfully update customerinfo")
    Catch ex As Exception
        MsgBox(ex.Message)
    Finally
        cn.Close()
    End Try
End Sub