如何向 Access 数据库添加记录 - Visual Basic

Question

我做了一个测验，应该将用户的高分存储在数据库中，但是我一直收到错误提示“不允许更改 'ConnectionString'

这是我的代码：

Imports System.Data.OleDb
Public Class Pure

Dim pro As String
Dim connstring As String
Dim command As String
Dim myconnection As OleDbConnection = New OleDbConnection

这是应该将高分添加到访问数据库的其余代码

Private Sub btnSummary_Click(sender As Object, e As EventArgs) Handles btnSummary.Click
        pro = "provider=microsoft.ACE.OLEDB.12.0;Data Source=flashcard login.accdb" 'Establish connection with database
        connstring = pro
        myconnection.ConnectionString = connstring
        myconnection.Open() 'Open connection
        If lblScore11.Text > lblHighScore.Text Then 'If current socre is greater than high score
            lblScore11.Text = lblHighScore.Text
            command = " insert into results ([score]) values ('" & lblHighScore.Text & "')"
            Dim cmd As OleDbCommand = New OleDbCommand(command, myconnection) 'Establish connection
            cmd.Parameters.Add(New OleDbParameter("score", CType(lblHighScore.Text, String)))
        End If
    End Sub

我在末尾添加了这个 try-catch 语句（在 if 语句中）

        Try
            cmd.ExecuteNonQuery()
            cmd.Dispose()
            myconnection.Close()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

Answer 1

还有其他问题，但最重要的是您实际上需要运行查询：

cmd.ExecuteNonQuery()

另外，这个查询仍然很容易受到注入问题的影响。这种字符串替换 NEVER 对于 SQL 字符串是可以的：

 values ('" & lblHighScore.Text & "')"

这里是一个完整的重写，具有更好的模式：

Dim connString As String = "provider=microsoft.ACE.OLEDB.12.0;Data Source=flashcard login.accdb" 

Private Sub btnSummary_Click(sender As Object, e As EventArgs) Handles btnSummary.Click

    If lblScore11.Text <= lblHighScore.Text Then Return
    lblHighScore.Text = lblScore11.Text

    Using conn As New OleDbConnection(connSstring), _
          cmd As New OleDbCommand("INSERT INTO results ([score]) VALUES (?)", conn)
        'Use the actual OleDbType that maps to the database column and length here
        cmd.Parameters.Add("score", OleDbType.LongVarWChar).Value = lblScore11.Text
        conn.Open()
        cmd.ExecuteNonQuery()
    End Using
End Sub

如何向 Access 数据库添加记录 - Visual Basic

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