附加信息：用户 '' 登录失败。 SQL Server 2012

Question

我一直在解决这个问题：

Imports System.ComponentModel
Imports System.Data.SqlClient

Public Class Form1
    Dim MyConnection As SqlConnection = New SqlConnection("Server=DESKTOP-I0N45MV\SQL2012;Database=user;uid=;pwd=")
    Dim MyDataAdapter As New SqlDataAdapter()
    Dim MyDataAdapter1 As New SqlDataAdapter()
    Dim Result As String
    Dim Result1 As String

    Private Sub login_Click(sender As Object, e As EventArgs) Handles login.Click
        MyDataAdapter.SelectCommand = New SqlCommand()
        MyDataAdapter1.SelectCommand = New SqlCommand()

        MyDataAdapter.SelectCommand.Connection = MyConnection
        MyDataAdapter1.SelectCommand.Connection = MyConnection
        MyDataAdapter.SelectCommand.CommandText = "Select Username From users WHERE Username ='" & user_.Text & "'"
        MyDataAdapter1.SelectCommand.CommandText = "Select Password From users WHERE Password ='" & pass_.Text & "'"
        MyConnection.Open()
        Result = MyDataAdapter.SelectCommand.ExecuteScalar()
        Result1 = MyDataAdapter1.SelectCommand.ExecuteScalar()
        MyConnection.Close()

Answer 1

首先不要使用这个：
MyDataAdapter.SelectCommand.CommandText = "SELECT Username FROM users WHERE Username ='" & user_.Text & "'"因为它会让你的代码可以通过 SQL 注入来注入，请改用存储过程或参数化查询。

其次，我不明白您为什么要使用两个查询。
你不能只用像SELECT Username FROM users WHERE Username = 'foo' AND Password = 'bar' ，然后只使用这个查询的结果吗？

第三，我建议您将连接字符串作为参数传递给您的项目。 如果您正在编写WinForms项目，您可以像这样访问它： Dim connection As New SqlConnection(My.Settings.connectionString)

最后，因为这就是你所问的，你的连接字符串应该看起来像Server=YourServerName;Database=YourDBName;Trusted_Connection=True; .
如果您在 SQL Server 上使用 Windows 身份验证，它应该看起来像这样Server=myServerAddress;Database=myDataBase;User Id=myUsername; Password=myPassword; Server=myServerAddress;Database=myDataBase;User Id=myUsername; Password=myPassword; , 如果您使用用户名和密码进行身份验证。