试图让php查询在一天中发生一次

Question

I want this Code to do query just once in a day means after it happened the code will be hidden or disabled some how, is that possible ? thanks :)

$time = date("G");
if($time >= 12 && (isset($_SESSION['UserName']))){
    mysql_query("Update users set diamonds = diamonds+1 where username = 'NaiTreNo'");
}

Answer 1

Of course a cronjob is a start, but even cronjobs might fail or you might have multiple machines for the same database.

Extend the table with a column last_daily_diamond datetime, which you set when the user gets its diamond, so:

update users set diamonds=diamonds+1, last_daily_diamond = now()
where username='flaschenpost' and last_daily_diamond < now() - interval 24 hour
;

If you mean calendar days and not 24-hour-days, then use not datetime, but date column for last_daily_diamond.

update users set diamonds=diamonds+1, last_daily_diamond = curdate()
where username='flaschenpost' and last_daily_diamond < 

curdate() ;

If user comes after 10 days and should get 10 diamonds (this decision is up to your customer/boss/yourself!), it gets

update users set diamonds=diamonds+1, last_daily_diamond = last_daily_diamond + interval 1 day
where username='flaschenpost' and last_daily_diamond < 

curdate() ;

(if the query itself is send often enough)

or a bit more complicated (not tested yet)

update users set diamonds=diamonds+
(@given := round((unix_timestamp(curdate()) - unix_timestamp(last_daily_diamond))/(24*60*60))), 
last_daily_diamond = curdate() + interval @given days
where username='flaschenpost' and last_daily_diamond < 

curdate() ;

If you can not extend the users table, you could also create an extra table for this and join to users table.