所以我在vb.net上遇到了我的登录代码问题，并且想知道是否有人可以建议我的代码有什么问题？
我得到的错误是：
System.Data.dll中出现'System.Data.SqlClient.SqlException'类型的异常，但未在用户代码中处理
附加信息：数据类型text和varchar在等于运算符中不兼容。
代码。
Imports System.Data.SqlClient
Partial Class Login Inherits System.Web.UI.Page
Protected Sub btnlogin_Click(sender As Object, e As EventArgs) Handles btnlogin.Click
Dim conn As New SqlConnection
Dim cmd As New SqlCommand
Dim dr As SqlDataReader
Dim LogEmail As String
Dim LogPassword As String
LogEmail = txtLogEmail.Text
LogPassword = txtLogPword.Text
conn.ConnectionString = "Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\User\Documents\Visual Studio 2015\WebSites\myAppointments\App_Data\Database.mdf;Integrated Security=True"
cmd.Connection = conn
conn.Open()
cmd.CommandText = "SELECT EmailAddress, Password FROM PatientDetails WHERE EmailAddress = '" & txtLogEmail.Text & "' and Password = '" & txtLogPword.Text & "'"
dr = cmd.ExecuteReader
If dr.HasRows Then
lblLogin.Text = "Login Successful!"
Else
lblLogin.Text = "Login Unsuccessful! :("
End If
conn.Close()
End Sub
End Class
答案 0 :(得分：0)
import React from 'react';
import ReactDOM from 'react-dom';
import { Router, Route, Link, browserHistory, IndexRoute } from 'react-router'
import { CreateAccount } from './createaccount';
import { Menus } from './menu';
import { DiscoverApp } from './discover'
import { northAmerica } from './northAmerica'
import { southAmerica } from './southAmerica'
import { europe } from './europe'
import { africa } from './africa'
import { asia } from './asiaME'
import { australia } from './australia'
import * as map from './jquery-jvectormap-2.0.3.min.js'
import * as world from './jquery-jvectormap-world-mill-en.min.js'
ReactDOM.render((
<Router history = {browserHistory}>
<Route path="/" component={CreateAccount}/>
<Route path="/menu" component={Menus}/>
<Route path="/discover" component={DiscoverApp}/>
<Route path="/NorthAmerica" component={northAmerica}/>
<Route path="/SouthAmerica" component={southAmerica}/>
<Route path="/Europe" component={europe}/>
<Route path="/Asia" component={asia}/>
<Route path="/Africa" component={africa}/>
<Route path="/Australia" component={australia}/>
</Router>
), document.getElementById('root'));
字段中的[EmailAddress]字段或[Password]字段很可能属于[PatientDetails]类型。您需要将基础数据类型更改为text或varchar才能使用此查询。
更重要的是，您的查询很容易受到SQL注入攻击，因为您既没有清理，也没有对这些输入进行清理，也没有参数化。想象一下，如果有人在用户名框中输入以下内容：
nvarchar当您检查密码时，他们只是删除了整个表格...
答案 1 :(得分：0)
除了Tim所说的，EmailAddress或Password字段都没有理由是text类型。使用nvarchar(255)就足够了。