Question

我有一个使用MySQL数据库的数据库登录。如果用户登录成功，则会将用户带到菜单屏幕。一切正常，但我想要做的就是将用户带到一个单独的管理界面，如果他们的用户组＆＃34;数据库中的字段表示＆＃34; Admin＆＃34;

我到目前为止，所有内容的工作代码如下：

Imports MySql.Data.MySqlClient

Public Class frmLogin
    Dim MysqlConn As MySqlConnection
    Dim command As MySqlCommand
    Dim reader As MySqlDataReader

    Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click

        MysqlConn = New MySqlConnection
        MysqlConn.ConnectionString =
        "server=localhost;port=3307;userid=root;password=Djmmcm93;database=dojodb"

        Dim reader As MySqlDataReader ' had to be declared inside the button or would not work


        Try
            MysqlConn.Open() ' opening the connection to the DB
            Dim query As String
            query = "select * from dojodb.userinfo where UserID='" & txtUserID.Text & "' and Password='" & txtPassword.Text & "'"
            command = New MySqlCommand(query, MysqlConn)
            reader = command.ExecuteReader 'executes the command and reads data from db

            Dim count As Integer
            count = 0
            While reader.Read
                count = count + 1
            End While

            If count = 1 Then
                MessageBox.Show("Welcome!")
                Me.Hide()
                frmUserMenu.Show()
            ElseIf count > 1 Then
                MessageBox.Show("username and password are duplicated!") 'Only here as test
            Else
                MessageBox.Show("username and password are incorrect!")
            End If

            MysqlConn.Close()

        Catch ex As Exception
            MessageBox.Show(ex.Message) 'printing the exact error to help future testing if needed
        Finally
            MysqlConn.Dispose()
        End Try
    End Sub
End Class

Answer 1

我注意到并改变的第一件事是SELECT *。出于性能原因，您应该尝试永远不要选择*并指定所需的列。如果有更多列，请随意添加。

然后我调整了你的代码，希望它可以帮助你：

Public Class frmLogin
    Dim MysqlConn As MySqlConnection
    Dim command As MySqlCommand
    Dim reader As MySqlDataReader

    Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click

        MysqlConn = New MySqlConnection
        MysqlConn.ConnectionString =
        "server=localhost;port=3307;userid=root;password=Djmmcm93;database=dojodb"

        Dim reader As MySqlDataReader ' had to be declared inside the button or would not work


        Try
            MysqlConn.Open() ' opening the connection to the DB
            Dim query As String
            query = "select UserID,Password from dojodb.userinfo where UserID='" & txtUserID.Text & "' and Password='" & txtPassword.Text & "'"
            Dim userStatus = "select UserGroup from dojodb.userinfo where UserID='" & txtUserID.Text & "' and Password='" & txtPassword.Text & "'"
            command = New MySqlCommand(query, MysqlConn)
            reader = command.ExecuteReader 'executes the command and reads data from db

            If UserGroup = "Admin" Then

                'Send to admin page here


            Else            

                Dim count As Integer
                count = 0
                While reader.Read
                count = count + 1
                End While

                If count = 1 Then
                MessageBox.Show("Welcome!")
                Me.Hide()
                frmUserMenu.Show()
                ElseIf count > 1 Then
                MessageBox.Show("username and password are duplicated!") 'Only here as test
                Else
                MessageBox.Show("username and password are incorrect!")
                End If

                MysqlConn.Close()
            End If

        Catch ex As Exception
            MessageBox.Show(ex.Message) 'printing the exact error to help future testing if needed
        Finally
            MysqlConn.Dispose()
        End Try
    End Sub
End Class

Answer 2

您可以尝试修改代码的下一部分：

Dim count As Integer
Dim UserGroup As String = ""   ' <───────  Insert this line.
count = 0
While reader.Read
    count = count + 1
    UserGroup = reader("UserGroup").ToString   ' <───────  Insert this line ("UserGroup" is the name of the field in the UserInfo table).
End While

If count = 1 Then
    MessageBox.Show("Welcome!")

    If UserGroup = "Admin" Then   ' ' <───────  Insert this If to verified UserGroup.
        ' bring the user to separate admin screen
    Else
        Me.Hide()
        frmUserMenu.Show()
    End If
ElseIf count > 1 Then
    MessageBox.Show("username and password are duplicated!") 'Only here as test
Else
    MessageBox.Show("username and password are incorrect!")
End If

VB.NET SQL数据库登录

2 个答案: