php - 查询数据库时收到错误

Question

我正在尝试为我的网站制作一个登录表单，其中用户名和密码已经存储在 mydb 的表用户中。我创建了 checklogin.php 来创建从我的网站到 mydb 的连接，然后检查登录凭据。

这是 checklogin.php 的代码:

<?php
$host="127.0.0.1:3306"; // host name
$username="root"; // mysql usrname
$password=""; // mysql password
$db_name="mydb"; // db name
$tbl_name="user"; // table name

//Connect to server and select database
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die(mysql_error());

//User name and password sent from form
$myusername=$_POST['myusername'];
$mypassword=$_POST['mypassword'];

$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);

if($count==1)
{   // register $myusername, $mypassword and redirect file to loginSuc.php
    session_register("myusername");
    session_register("mypassword");
    header("location:loginSuc.php");
}
else 
{
    echo "wrong username or password";
}
?>

现在我已将缺少的组件添加到之前的代码中，当我运行时，我现在收到指向第 13、14 和 19 行的错误。

错误是:

Notice: Undefined index: myusername in C:\wamp\www\HTML 5, CSS 3 & PHP\checklogin.php on line 13/14/19 with the string "wrong username or password" appearing underneath

再次坚持如何解决这个问题 - 已修复

通过添加一些额外的代码来修复第 13,14 和 19 行的错误。现在有错误:

"Parse error: syntax error, unexpected T_IF in C:\wamp\www\HTML 5, CSS 3 & PHP\checklogin.php on line 27"

<?php
$host="127.0.0.1:3306"; // host name
$username="root"; // mysql usrname
$password=""; // mysql password
$db_name="mydb"; // db name
$tbl_name="user"; // table name

//Connect to server and select database
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die(mysql_error());

//User name and password sent from form
$myusername=$_POST["myusername"];
$mypassword=$_POST["mypassword"];

// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);
$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);

// Mysql_num_row is counting table row
$count=mysql_num_rows($result)

if($count==1)
{   // register $myusername, $mypassword and redirect file to loginSuc.php
    session_register("myusername");
    session_register("mypassword");
    header("location:loginSuc.php");
}
else 
{
    echo "wrong username or password";
}
?>

高于固定

现在我得到了 checklogin.php 没有错误，我现在正在使用:

<?php

$host="127.0.0.1:3306"; // host name
$username="root"; // mysql usrname
$password=""; // mysql password
$db_name="mydb"; // db name
$tbl_name="user"; // table name

//Connect to server and select databasemysql_connect
mysql_connect($host, $username, $password, $db_name) or die(mysql_error());

if($_POST)
{   
    $myusername=$_POST["myusername"];
    $mypassword=$_POST["mypassword"];

    $sql="SELECT * FROM ".$tbl_name." WHERE myusername=".$myusername." and mypassword=".$mypassword;
    $result=mysql_query($sql);

    // register $myusername, $mypassword and redirect file to loginSuc.php
    session_register("myusername");
    session_register("mypassword");
    header("location:loginSuc.php");

}
else 
{
    echo "wrong username or password";
}

?>

但我仍然遇到问题。每当我尝试通过 loginpage.html 中的表单登录时，它会转到 checklogin.php 但 checklogin.php 只会显示“密码或用户名错误”。当我按下没有用户名或密码的提交按钮时，当我输入不正确的用户名和密码时，甚至当我使用我在 mydb 的用户表中作为示例放置的用户名和密码时，我都会得到这个。 (在用户表中，我有用户 ID、用户名和密码字段)。

这是我的 loginpage.html 开头的 php:

<?php 
session_start();
if(!session_is_registered(myusername))
{
header("location:checklogin.php");
}
?> 

这是表格(我使用了 html5 和 twitter 引导网格代码):

<form class="form-horizontal" method="post" action="checklogin.php">
    <div class="form-group">
        <label for="myusername" class="control-label col-xs-3">Username</label>
        <div class="col-xs-6">
            <input type="text" class="form-control" id="myusername" placeholder="Library card number">
        </div>
    </div>
    <div class="form-group">
        <label for="mypassword" class="control-label col-xs-3">Password</label>
        <div class="col-xs-6">
            <input type="password" class="form-control" id="mypassword" placeholder="Password">
        </div>
    </div>
    <div class="form-group">
        <div class="col-xs-6">
        </div>
    </div>
    <div class="form-group">
        <div class="col-xs-offset-2 col-xs-24">
            <button type="submit" class="btn btn-primary">Login</button>
        </div>
    </div>
</form> 

Answer 1

您应该为 mysql_select_db 使用变量名不是文字字符串。

$host="127.0.0.1:3306"; // host name
$username="root"; // mysql usrname
$password=""; // mysql password
$db_name="mydb"; // db name
$tbl_name="user"; // table name

//Connect to server and select database
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db($db_name)or die(mysql_error()); // <-- $db_name instead of 'db_name'

//User name and password sent from form
$myusername=$_POST['myusername'];
$mypassword=$_POST['mypassword'];

$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);

if($count==1)
{   // register $myusername, $mypassword and redirect file to loginSuc.php
    session_register("myusername");
    session_register("mypassword");
    header("location:loginSuc.php");
}
else 
{
    echo "wrong username or password";
}