MySQL: filtering results from a list of id's

A short while ago I posted about testing if a variable exists in a list and I spoke about the MySQL “IN” keyword.

I realised this week that not everyone knows about the MySQL “IN” keyword, so I’ve decided to explain this very handy SQL keyword.

Lets say you have a user table with the following fields; user_id, username, password. You have a list of user ids (eg 1, 3, 5) and you want to draw the usernames and passwords for these users.

You could use the following SQL code:

SELECT `username`, `password` FROM `user`
WHERE `user_id` = 1 AND WHERE `user_id` = 3 AND WHERE `user_id` = 5;

Now while this is correct and will return the required results, it is quite a bit to code (especially if you have a larger list of user ids). Here comes the “IN” keyword to save us.

SELECT `username`, `password` FROM `user` WHERE `user_id` IN (1, 3, 5);

See how easy that is. Now if you have a much larger list (or the list grows) you simply add the user ids to the comma delimited list. Less time spent, and the same result. I’m all about the shortcuts….

Life of a developer

It has been a while since I have posted here, mainly due to the time consuming period that is the festive season and also because I am discovering that I am getting fairly annoyed by Drupal as a blog tool and am trying out the new WordPress as an alternative.

For now I have a small post on something that many people aren’t aware of but is VERY handy, the ternary operator.

Basically it is a shortcut to do a simple if-then-else statement in one line when you are performing fairly simple checks for a single value. I tend to use it a lot when checking for GET or POST variables.

So:

$getContents = (isset($_GET) ? $_GET : array());

would check if the $_GET variable array is set, if it is return its contents to $getContents and if not return and empty array to $getContents.

Much easier that coding:

$getContents = array();
if (isset($_GET)){
$getContents = $_GET;
}

P.S. Just on a side note, if you are new to PHP and want to use this code to check for and receive your $_GET contents, dont forget to sanatize your data as well (hmm I think I see a new post topic)

Delving deeper into the PHP lake…testing if a variable exists in a list

As a PHP developer of almost four years now, I often still come across little problems in coding that make me do the good ol Google search to find the answer. (someday I will have memorised the entire PHP manual, but today is not that day ;-).

Anyway today I was asked about how to do a IN LIST type comparison in PHP. (similar to the mysql IN statement).

A few google searches later revealed that there exists no such PHP command, however the in_array function can be used to perform the task:

$myArray = array(1, 2, 3, 4, 5);

if (in_array($var, $myArray)){
// do some code.
}

I guess one could also combine the two as follows:

if (in_array($var, array(1, 2, 3, 4, 5))){
// do some code.
}

I’ll have to test that one, but you get the idea…

Simple PHP increment function

Whenever I have to output a numbered list of data I usually run the following code to achieve the required result.

$counter = 0;
// for loop that does all the required code
$counter++;
// end for

but I have discovered a lovely little function that does all this for me.

function increment(&$counter){
$counter++;
return $counter
}

now I simply call

increment($whichever_counter)

and it automatically outputs the next numeric.

Great! Simple and easy to use…..that’s the way to code.

My first published article.

Something of a first for me. I recently started playing around with the CakePHP framework again. I have had some (little) experience with it in the past and with the launch of two CakePHP books I decided it was high time I learned how to use this awesome framework properly.

A few days later I was trying to find a way to integrate my favourite html editor into the framework itself and after a lot of googling, trial and error and a little luck I managed to find a simple, reusable way to integrate the editor into the framework. As this was very helpful to me I posted an article on the CakePHP bakery, and the chaps over there deemed it worthy enough to be published.

You can read it here . Please feel free to send me your comments.

I’m just kinda chuffed the published it. 😉