Question

Private Sub ForgotPasswordPage1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim table2 As New DataTable
    Dim cmd As New MySqlCommand
    Dim cmd1 As New MySqlCommand
    Dim da As New MySqlDataAdapter
    Dim da2 As New MySqlDataAdapter
    Dim con = New MySqlConnection
    con.ConnectionString = "server=127.0.0.1;userid=root;password=;database=pharma"
    Try
        'we open Connection
        con.Open()

        With cmd
            .Connection = con
            .CommandText = "SELECT `security_question_1` from pharma.account_admin where `u_name`='" & Login.u_name.Text & "';"
        End With

        'declare dt as new datatable
        Dim dt As New DataTable
          Dim dt2 As New DataTable
        With sq
            da.SelectCommand = cmd
            'it fills the da values into dt
            da.Fill(dt)
            'dt provides the data surce of combobox
            .DataSource = dt
            'specify the what to display
            .DisplayMember = "security_question_1"

            'and the value
            .ValueMember = "security_question_1"

        End With


        With cmd1
            .Connection = con
            .CommandText = "SELECT `security_question_2` from pharma.account_admin where `u_name`='" & Login.u_name.Text & "';"
        End With
        With sq
            da.SelectCommand = cmd1
            'it fills the da values into dt
            da.Fill(dt)
            'dt provides the data surce of combobox
            .DataSource = dt
            'specify the what to display
            .DisplayMember = "security_question_2"

            'and the value
            .ValueMember = "security_question_2"

        End With
    Catch ex As Exception

这是我的代码。我想要安全问题1和安全问题2，这是我的数据库中的两个不同的字段，可以插入组合框中。

Answer 1

我的代码中最重要的是使用参数。此更改将有助于保护您的数据库免受恶意输入。我还使用了安全问题1和2的别名。（select命令中的As Question。）仔细检查用户名的数据类型。我猜到varchar但它可能是其他东西。相应地更改MySalDbType。使用DataTable.Load将第二个查询中的记录添加到数据表中。实际上，我认为这两个选择可以作为联盟运行。如果您只回到2个问题，那么我会在一个查询中选择两个问题，使用datareader并手动将值添加到组合框中。 Using / End Using语句确保实现IDisosable的对象可以尽快释放其非托管资源。

Using cmd As New MySqlCommand
            Using da As New MySqlDataAdapter
                Using con = New MySqlConnection("server=127.0.0.1;userid=root;password=;database=pharma")
                    Try
                        With cmd
                            .Connection = con
                            .CommandType = CommandType.Text
                            .CommandText = "SELECT `security_question_1` As Question from pharma.account_admin where `u_name`= @UserName;"
                            .Parameters.Add("@UserName", MySqlDbType.VarChar).Value = Login.u_name.Text
                        End With
                        Using dt As New DataTable
                            da.SelectCommand = cmd
                            da.Fill(dt)
                            cmd.CommandText = "SELECT `security_question_2` As Question from pharma.account_admin where `u_name`= @UserName;"
                            con.Open()
                            Using dr As MySqlDataReader = cmd.ExecuteReader
                                dt.Load(dr)
                                con.Close()
                                ComboBox1.DataSource = dt
                                ComboBox1.DisplayMember = "Question"
                                ComboBox1.ValueMember = "Question"
                            End Using
                        End Using
                    Catch ex As Exception
                    End Try
                End Using
            End Using
        End Using

如何在vb.net中将两个数据库字段放到一个组合框中？

1 个答案: