Php 如何在数据库中插入用户注销的时间？

我成功地编写了登录的代码…当用户登录时，登录的时间写在数据库中

session_start();
    $query = mysql_query("SELECT * FROM users");
    $result = mysql_fetch_array($query);


    if(!empty($_POST['username']) && !empty($_POST['password'])){           
        $username = ($_POST['username']);
        $password = ($_POST['password']);           
        $username = stripslashes($username);
        $password = stripslashes($password);            
        $username = mysql_real_escape_string($username);
        $password = mysql_real_escape_string($password);            
        $_SESSION['username'] = $username;
        $_SESSION['password'] = $password;

$result = mysql_query("SELECT * FROM users WHERE username = '$username' AND status = '1'"); 
 if(mysql_num_rows($result) == 1) {
                mysql_query("INSERT INTO entry(id, username_id, entry_time) VALUES ('', 'bkrpan', NOW()) "); 
                header("Location: admin.php"); 
                exit; }

        $result = mysql_query("SELECT username FROM users WHERE username = '$username' AND password = '$password'");
            if(mysql_num_rows($result) == 1) {
                mysql_query("INSERT INTO entry(id, username_id, entry_time) VALUES ('', '$username', NOW()) "); 
            $_SESSION['username'] = $username;
            $_SESSION['password'] = $password;
            header("Location: users.php");
            exit; }
            echo "Login failed! You will be redirected.";
            echo "<meta http-equiv=\"refresh\" content=\"2;URL=index.php\">";
            } 

    else {
        echo "Login failed! You will be redirected.";
        echo "<meta http-equiv=\"refresh\" content=\"2;URL=index.php\">";
    }

     session_destroy();

但是…现在我不知道如何制作注销代码。 这是我做的东西，但不起作用

 <?php
 mysql_connect("localhost", "root", "") or die("cannot connect"); 
 mysql_select_db("zavrsni_rad") or die("cannot select DB");
 session_start();
 $username = $_SESSION['username'];
 $sql = "SELECT * FROM users WHERE username = ".$username." AND password = ".$password;
 $result = mysql_query($sql); 
 if(mysql_num_rows($result) == 1) {
$sql_2 = "INSERT INTO entry(username_id, entry_time) VALUES (".$username.", NOW()        )";
mysql_query($sql_2); 
 }
session_destroy();
 header("location: index.php");
 ?>

---

您忘记了查询中的单引号，因此无法获得$password的值

$sql = "SELECT * FROM users WHERE username = '".$username."' AND password = '".$password."'";

$sql_2 = "INSERT INTO entry(username_id, entry_time) VALUES ('".$username."', NOW())";

为清晰起见进行了更新

<?php
session_start();

// check that the session exists first
if(isset($_SESSION['username'])) {

    // you should put your db connection in a config.php file and use mysqli or PDO - what you're using is depreciated
    mysql_connect("localhost", "root", "") or die("cannot connect"); 
    mysql_select_db("zavrsni_rad") or die("cannot select DB");

    // don't think I'd store password in a session...
    // also, is username UNIQUE in your database?
    // also, also, ALWAYS escape (sanitize) your database input to prevent agains SQL injection

    $sql = "SELECT username, password 
    FROM 
        users 
    WHERE 
        username = '".mysql_real_escape_string($_SESSION['username'])."' 
    AND 
        password = '".mysql_real_escape_string($_SESSION['password'])."'";
    $result = mysql_query($sql) or die('sql: '.mysql_error()); 

    if(mysql_num_rows($result) > 0) {
        $sql_2 = "INSERT INTO entry(username_id, entry_time) VALUES ('".mysql_real_escape_string($_SESSION['username'])."', NOW())";
        mysql_query($sql_2) or die('sql2: '.mysql_error()); 

        session_destroy();
        header("location: index.php");
    } else {
        echo 'There was an error. You have not been logged out.';
    }
}

---

它不起作用意味着什么？你有白色的屏幕吗？错误消息？没有添加任何内容？添加了错误的数据？正确的数据，到了错误的地方？这意味着数据库是空的…时间没有添加到数据库中…我被重定向到index.php，这很好检查会话是否首先存在-它存在于login.php中--另外，用户名在数据库中是唯一的吗？-它是---我复制了你的代码…它和以前一样…我没有时间写在数据库中检查会话的存在是无害的，可以避免问题-在做任何重要的事情之前做这件事是个好主意。密码设置好了吗？尝试将mysql\u error添加到两个查询中，看看您的错误是什么：mysql\u query$sql\u 2或diemsql\u error；哦，会话是在login.php中设置的，这并不意味着它将存在于其他脚本中。如果用户退出浏览器，然后返回logout.php，则不会设置会话，但您将运行代码。这就是为什么要检查会话是否已设置。