Question

我正在尝试建立与MySQL服务器的连接，从文本框中获取输入，使用该信息运行查询并将其存储在列表框中。

为了更进一步，我希望在文本框中键入时更新列表框。

每当我跑步时，vb都没有填充。我甚至尝试将查询更改为基本的，从securePasswordList.users中选择*;我无法得到任何东西。

有任何建议或批评吗？谢谢！还在学习VB相当多的东西......还有很长的路要走。

  Imports MySql.Data.MySqlClient

Public Class Reveal
    Public Property MyDataClass As SecurePasswordList
    Dim lastNameInput As String
    Dim firstNameInput As String
    Dim connStr As String = "server=0.0.0.0;user=johndoe;database=securePasswordList;port=3306;password=password;"
    Dim conn As New MySqlConnection(connStr)
    Dim SQL As String = "select password from securePasswordList.users where LAST_NAME like ' " & lastNameInput & "%'"
Dim cmd As MySqlCommand = New MySqlCommand(SQL, conn)

    Private Sub Reveal_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub

    Private Sub firstName_TextChanged(sender As Object, e As EventArgs) Handles lastNameTextBox.TextChanged
        lastNameInput = lastNameTextBox.Text
        listBox.Items.Add(cmd)
    End Sub



    Private Sub lastName_TextChanged(sender As Object, e As EventArgs) Handles firstNameTextBox.TextChanged
        firstNameInput = firstNameTextBox.Text
    End Sub

    Private Sub listBox_SelectedIndexChanged(sender As Object, e As EventArgs) Handles listBox.SelectedIndexChanged

    End Sub
 End Class

Answer 1

您的一个问题是您实际上并未在任何地方执行MySqlCommand。另外，我想指出this link，因为在构建select-string的方式中，当前代码中存在潜在的安全问题。

以下是如何检索密码的示例：

Private Function RetrievePassword(ByVal lastName As String) As String
    Using conn As New MySqlConnection(connStr)
        Using comm As New MySqlCommand(query, conn)
            comm.Parameters.AddWithValue("@LastName", lastName & "%'")

            Dim result As Object = comm.ExecuteScalar()

            If result Is Nothing Then
                handle as you like...
            End If

            Return result.ToString
        End Using
    End Using
End Function

查询将包含参数的占位符，如下所示：

    Private Const query As String =
         "select password from securePasswordList.users where LAST_NAME like @LastName"

使用Visual Basic执行MySQL查询

1 个答案: