Tag Archives: Programming

How to validate e-mail address in MySQL

Most people validate e-mail addresses in a normal programming language, such as PHP and that is a very good idea when you process user input and such, however sometimes you want to validate data already entered in a database.

Take this example: you have a comments table where each person can enter an e-mail address, but since it’s an optional field you don’t even validate the input. However when you need to send a newsletter you don’t want to process all fields and validate one by one, you want to use a single query and just get all e-mail addresses (eventually by adding additional rules as well), so here’s how you can do it in MySQL:

FROM `m_comment`
WHERE `comment_url`
REGEXP ‘(.*)@(.*)\.(.*)’

Sure, you can optimize the query, but it’s a simple regular expression which .. well, in most cases is good enough.

How to make multiple updates using a single query in MySQL

As you might know it’s quite easy to make multiple INSERTs in a single query, like this:

(id, title)
('1', 'Lord of the Rings'),
('2', 'Harry Potter');

However, for some strange reason you can’t do multiple changes to a table in a single UPDATE query like this:

UPDATE mytable
SET (title='Great Expectations' WHERE id='1'),
(title='War and Peace' WHERE id='2');

Continue reading How to make multiple updates using a single query in MySQL

How to crash IE6 with one line

Hamachiya2 found out a way to crash Internet Explorer 6 (and on some systems even the entire operating system).


A simple line (which you can test it here) – no one figured out why caused an exception in mshtml.dll (and knowing Microsoft we’re most likely never going to find out the answer to that).

Internet Explorer 6 crash

The code doesn’t have any problems on Firefox, IE7 or other browsers. Well, I hope you’re not still using IE6 – although according to these browser statistics 37.3% were still using it in June 2007.