MySQL查询为真后，如何挂接到触发的事件？

Question

How does one create a PHP script that checks the MySQL row consistently and if a set query is matched, it starts an event, such as sending an email?

For example, on query match Fire start email:

To: me@me.com
From: php@trigger.com
Subject: Set query met, auto email complete.

It would be around MySQL5. I'm stuck on this. Am I best to do it in Perl or similar? Perhaps it could also email various users? (This isn't the hard bit. :P)

Answer 1

Using cron or similar scheduler involves polling , which works but is brute force and ignorance . I can't recommend it: there's a time delay between when the row changes and when cron executes the checking program; repeated checking is a waste of resources.

The elegant solution is database trigger, see Using Triggers and Can triggers call an external application through a UDF? . You will get an event whenever your table row is on fire or something, and your email sending program is called immediately.

If you want to use Perl, Email::Simple / Email::Sender is nifty.

Answer 2

You can use PHP or Perl or any other programming language you like.

Create a cronjob to execute your script every X hours.

For example php queryDatabase.php .

That's it.