mysql - 使用 MySQL 数据库的 VB.NET 登录表单

Question

请有人帮我解决以下问题。

我创建了一个名为 dbhr 的数据库，并在其中创建了一个名为 user 的表，其中包含两个字段“用户名”和“密码”，数据类型为 VARCHAR。我有一个带有两个文本框(tbxUsername、tbxPassword)和一个 OK 按钮的登录表单。我已连接我的数据库以验证用户名和密码。但它总是给我错误的密码信息。我不知道我哪里出错了。请帮忙。

我使用 MySQL Workbench 6.1

提前致谢。

这是 VB.NET 登录按钮代码。

Imports MySql.Data.MySqlClient

Public Class Login

    Dim mydbcon As MySqlConnection
    Dim COMMAND As MySqlCommand

    ' TODO: Insert code to perform custom authentication using the provided username and password 
    ' (See http://go.microsoft.com/fwlink/?LinkId=35339).  
    ' The custom principal can then be attached to the current thread's principal as follows: 
    '     My.User.CurrentPrincipal = CustomPrincipal
    ' where CustomPrincipal is the IPrincipal implementation used to perform authentication. 
    ' Subsequently, My.User will return identity information encapsulated in the CustomPrincipal object
    ' such as the username, display name, etc.

    Private Sub OK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OK.Click
        mydbcon = New MySqlConnection
        mydbcon.ConnectionString = "server=localhost;userid=root;password=rootword;database=hrdb"
        Dim reader As MySqlDataReader

        Try
            mydbcon.Open()
            Dim Query As String
            Query = "select * from user where username= ' " & tbxUsername.Text & "' and password= ' " & tbxPassword.Text & "' "
            COMMAND = New MySqlCommand(Query, mydbcon)
            reader = COMMAND.ExecuteReader

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

            End While

            If count = 1 Then
                MessageBox.Show("Username and password are correct")
            ElseIf count > 1 Then
                MessageBox.Show("Username and password are duplicate")
            Else
                MessageBox.Show("Username and password are wrong")
            End If
            mydbcon.Close()
        Catch ex As MySqlException
            MessageBox.Show(ex.Message)
        Finally
            mydbcon.Dispose()
        End Try

    End Sub

请点击以下链接查看数据库表记录和数据类型。

点击here !

Answer 1

行中有一些额外的空格

Query = "select * from user where username= ' " & tbxUsername.Text & "' and password= ' " & tbxPassword.Text & "' "

我会改成

Query = String.Format("SELECT * FROM user WHERE username = '{0}' AND password = '{1}'", Me.tbxUsername.Text.Trim(), Me.tbxPassword.Text.Trim())

我会使用 String.Format() 使其更清晰，减少忽略那些额外空格的机会。