Use PHP to determine if the user has logged in for the first time that day

Foreword

I was working on a project some time ago, and they asked me to automatically give out points when I log in for the first time every day.
Signing in didn’t give you points. I was depressed for a few seconds.
After searching on Baidu for a while to no avail, I finally came up with this method after much thought.
In other words, points are given silently. Others only know about this when they check their points, otherwise they would not know.

Bullshit

Since you need to log in every time you click on the user interface of the APP, this is easy to handle. I only need to judge whether it is the first time to log in every day when logging in.
But some things are easier said than done. How can we tell?
By querying the

users

database, I silently learned that there is a field

last_login

in the database. What is recorded is the Greenwich Mean Time timestamp of each user's login time.

Greenwich Mean Time

Greenwich Mean Time (old translation Greenwich Mean Time or Greenwich Mean Time; English: Greenwich Mean Time (GMT) refers to the standard time at the Royal Greenwich Observatory in the suburbs of London, England, because the prime meridian is defined on the longitude passing there. Since February 5, 1924, the Greenwich Observatory has distributed time adjustment information to the world every hour.

Timestamp

A timestamp (timestamp) is usually a sequence of characters that uniquely identifies a certain moment in time. Digital timestamp technology is a variant of digital signature technology.
So, as long as you log in, first query the last timestamp (the data has not been modified at this time) and record it; then modify the timestamp to the latest, record it, and compare the two timestamps. The

getdate()

function

getdate()

getdate() function is used here to obtain date/time information.

Implementation

So much has been said above, I’ll just post the code below.
This code is placed in the login function.
Assuming that $user_id has been determined, then the following method can be used to

/*查询到上一次登陆的last_login*/
    $sql = "SELECT last_login FROM users
            WHERE user_id = '$user_id'";

    /*获取上一次登录的格林威治时间的时间戳*/
    $last_login_old = $GLOBALS['db']->getOne($sql);

    /*获得上一次登陆日期*/
    $last_login_date_old = getdate($last_login_old);

    /*更新用户最后一次登陆时间last_login*/    
    $sql = "UPDATE users SET last_login = '" .gmtime(). "'
            WHERE user_id = '$user_id'";

    /*执行UPDATE*/
    $GLOBALS['db']->query($sql);

    /*查询到最新的登陆的格林威治时间的时间戳*/
    $last_login_new = gmtime();

    /*获得最新日期*/
    $last_login_date_new = getdate($last_login_new);

    /*进行比较，yday是一年的第几天*/
    /*若出现不等于的情况，就说明是当天第一次登陆*/
    if($last_login_date_old['year'] != $last_login_date_new['year'] ||
            $last_login_date_old['yday'] != $last_login_date_new['yday'])
    {
        /*判断成功，doSomething*/
    }

This function is also needed to support

 /**
     * 获得当前格林威治时间的时间戳
     * @return  integer
     */
    function gmtime()
    {
        return (time() - date('Z'));
    }

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