PHP学习-验证用户名密码

登录页：login.php

<?php
//登录
if(!isset($_POST['submit'])){exit('非法访问!');}
$username = $_POST['adname'];
$password = $_POST['adpass'];
//包含数据库连接文件
include('conn.php');
//检测用户名及密码是否正确
$check_query = mysql_query("select * from admin where ad_name='$username' and ad_code='$password' limit 1");
if($result = mysql_fetch_array($check_query)){
    //登录成功
    session_start();
    $_SESSION['username'] = $username;
    $_SESSION['userid'] = $result['ad_id'];
    echo $username,' 欢迎你！进入 <a href="my.php">用户中心</a><br />';
    echo '点击此处 <a href="login.html">注销</a> 登录！<br />';
    exit;
} else {
    exit('登录失败！点击此处 <a href="javascript:history.back(-1);">返回</a> 重试');
}
//注销登录
if($_GET['action'] == "logout"){
    unset($_SESSION['userid']);
    unset($_SESSION['username']);
    echo '注销登录成功！点击此处 <a href="login.html">登录</a>';
    exit;
}
?>

$_POST["a"]：获取post提交的数据a的值

mysql_query("select * from admin where ad_name='$username' and ad_code='$password' limit 1");执行一条MySQL查询

mysql_fetch_array($check_query)：获取根据如上数据表查询的一行信息