<h1>登录页面</h1>
<form  action="./dengluchuli.php" method="post">
<div>用户名：<input type="text" name="uid" /></div>
<div>密码：<input type="password" name="pwd" /></div>
<div><input type="submit" value="http://www.mamicode.com/登录"</div>
</form>

$uid = $_POST["uid"];
$pwd = $_POST["pwd"];
//1.造链接对象
$db = new MySQLi("localhost","root","456","asdadads");数据库名
//写SQL语句
$sql = "select mima from mydb where zhangh=‘{$uid}‘ and mima=‘{$pwd}‘";列名  表名
//执行
$reslut = $db->query($sql);
//取数据
$attr = $reslut->fetch_row();
if($attr[0]==$pwd && !empty($pwd))
{
    echo "登录成功";
    }
else
{
    echo"登录失败";
    }