Do Something When MYSQL Column Value Increments by 100

问题

I need to alert members of a site when their post count has reached a multiple of 100. Is it possible to run a function or echo something when a value in a mysql table reaches 100, 200, 300, etc?

Table structure:

username | password | email | posts 

I'm currently displaying their post count with:

$sql = mysql_query("SELECT `posts` FROM `user` WHERE username='$username'") or die(mysql_error());
$row = mysql_fetch_array($sql);

echo "<br /><h4>Your posts:</h4>" . " " . $row['posts'];

RESOLVED: I went with Marc's suggestion of using modulo, which suited my needs.

$sql = mysql_query("SELECT `posts` AS posts FROM `user` WHERE username='$username'") or die(mysql_error());
$row = mysql_fetch_array($sql);
$post = $row['posts'];

    if($post % 100 == 0) {

        mysql_query("INSERT INTO `posts` (name, message, message_raw) VALUES ('System', '$name has reached $post posts!', '$name has reached $post posts!')");

    }

回答1:

You need a modulo

Modulo operation. Returns the remainder of N divided by M.

Like this

SELECT username
FROM `user` 
WHERE username='$username' AND MOD(posts,100) = 0

And you can check the condition every time a user do a new post

回答2:

You can use triggers:

http://dev.mysql.com/doc/refman/5.5/en/triggers.html

or

Just create a cron job

来源：https://stackoverflow.com/questions/13590389/do-something-when-mysql-column-value-increments-by-100