MySQL: How can I count and limit the number of post submitted by the user every hour?

Question

I'm currently building a website where user can post(like a tweet on twitter), but I want to limit the number of post a user can submit on the website every hour.

This is what I have coded so far and it outputs the total number of post a user have.

$counter = mysql_query("SELECT COUNT(*) AS post_userID FROM post");
$num = mysql_fetch_array($counter);
$count = $num["post_userID"];
echo("$count");

if($count > 2) {
    echo("You have exceeded the posting limits, please try again in 24 hours");
}

MY POST TABLE

+------------+------------+------+-----+---------+----------------+
| Field      | Type       | Null | Key | Default | Extra          |
+------------+------------+------+-----+---------+----------------+
| postID     |int(11)     | NO   | PRI | NULL    | auto_increment |
| post_userID|int(11)     | NO   |     | NULL    |                |
| message    |VARCHAR(140)| NO   |     | NULL    |                |
| time       |datetime    | NO   |     | NULL    |                |
+------------+------------+------+-----+---------+----------------+

As you can see, I have a time(datetime) stored on my database and it holds the time when the post was submitted.

EXAMPLE:

+------------+------------+------------+----------+
| postID     |post_userID | message    | time     |
+------------+------------+------------+----------+
| 1          |    25      | Hello Mike |1413620228| 
| 2          |    26      | Hi John!   |1413620332|
+------------+------------+------------+----------+

Oh btw, my server type is MySQL.

Answer 1

One way to do this would be:

select count(*) from post
  where post_userID = 25
    and time >= date_add(now(), INTERVAL -1 HOUR);

This will give you the number of posts for the user in the past hour.

Link to SQL Fiddle

Answer 2

I would assume that you have a users table. Create a column in the users table called last_post_submit_time and then whenever a user submits the post save that time in it. Finally whenever a user submits a post check if the current time - it's last_post_submit_time >= one hour . I hope you get it...

Answer 3

You can simply divide the timestamp by 3600 and round it to integer, something like this:

SELECT
    ROUND(time/3600) AS hours_since_epoch
FROM
    posts
WHERE
    port_userID = <user> AND hours_since_epoch = ROUND(UNIX_TIMESTAMP(NOW())/3600)

This will return you the list posts user posted this hour (roughly).

Another way is to see how much the user has posted for the last hour:

SELECT
    COUNT(*)
FROM
    posts
WHERE
    port_userID = <user> AND time > UNIX_TIMESTAMP(NOW()) - 3600