附加信息：用戶 '' 登錄失敗。 SQL Server 2012

Question

我一直在解決這個問題：

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

首先不要使用這個：
MyDataAdapter.SelectCommand.CommandText = "SELECT Username FROM users WHERE Username ='" & user_.Text & "'"因為它會讓你的代碼可以通過 SQL 注入來注入，請改用存儲過程或參數化查詢。

其次，我不明白您為什么要使用兩個查詢。
你不能只用像SELECT Username FROM users WHERE Username = 'foo' AND Password = 'bar' ，然后只使用這個查詢的結果嗎？

第三，我建議您將連接字符串作為參數傳遞給您的項目。 如果您正在編寫WinForms項目，您可以像這樣訪問它： Dim connection As New SqlConnection(My.Settings.connectionString)

最后，因為這就是你所問的，你的連接字符串應該看起來像Server=YourServerName;Database=YourDBName;Trusted_Connection=True; .
如果您在 SQL Server 上使用 Windows 身份驗證，它應該看起來像這樣Server=myServerAddress;Database=myDataBase;User Id=myUsername; Password=myPassword; Server=myServerAddress;Database=myDataBase;User Id=myUsername; Password=myPassword; , 如果您使用用戶名和密碼進行身份驗證。