0) {
$_SESSION["username"] = $username;
echo "";
} else {
echo "";
}
} else if (isset($_REQUEST["register"]) or isset( $_REQUEST["add"])) {
// 从前端获取用户名，以及两次密码输入，以及邮箱
$username = $_REQUEST["username"];
$password = $_REQUEST["password"];
$password2 = $_REQUEST["password2"];
$email = $_REQUEST["email"];
// 判断两次密码是否一致
if ($password != $password2) {
echo "两次密码不一致";
exit;
}
// 判断用户名或邮箱是否已存在
$sql = "select * from users where username='$username' or email='$email'";
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) > 0) {
echo "用户名或邮箱已存在";
exit;
}
// 写sql语句，插入一条新的用户记录
$sql = "insert into users(username, password, email) values('$username', '$password', '$email')";
$result = mysqli_query($conn, $sql);
// 插入成功后，返回注册成功信息
if ($result) {
if(isset($_REQUEST["add"])) {
echo "";
} else {
echo "";
}
} else {
if(isset($_REQUEST["add"])) {
echo "";
} else {
echo "";
}
}
} else if (isset($_REQUEST["change"])) {
// 修改用户信息的操作
$userid = $_REQUEST["id"];
$username = $_REQUEST["username"];
$email = $_REQUEST["email"];
// 判断是否需要修改密码,判断密码的长度
if (strlen($_REQUEST["password"]) > 0) {
$password = $_REQUEST["password"];
$password2 = $_REQUEST["password2"];
if ($password != $password2) {
echo "";
exit;
}
// 更新用户名，密码，邮箱
// 存在逻辑漏洞，没有判断用户名是否存在，可以修改别人的用户名
$sql = "update users set username='$username', password='$password', email='$email' where id='$userid'";
$result = mysqli_query($conn, $sql);
if ($result) {
echo "";
} else {
echo "";
}
} else {
// 更新用户名和邮箱
$sql = "update users set username='$username', email='$email' where id='$userid'";
$result = mysqli_query($conn, $sql);
if ($result) {
echo "";
} else {
echo "";
}
}
} else if (isset($_REQUEST["del"])) {
// 删除用户
$userid = $_REQUEST["id"];
$sql = "delete from users where id='$userid'";
$result = mysqli_query($conn, $sql);
if ($result) {
echo "";
} else {
echo "";
}
} else {
echo "错误操作";
}
?>