One of the things that we needed throughout the site was a count of posts within various combinations of categories. Unfortunately, that kind of feature isn’t supported in Wordpress out-of-the-box. We’ll get a little technical here so those of you who just want the final solution–feel free to fast forward to the end of the article and grab the code.

How we did it

Wordpress is, as you probably know, a database driven platform, so first thing we need to do is to identify the right tables and understand their relationships in order to retrieve the correct data from them.

Basically our goal here is to identify terms that have taxonomy ‘category’ and filter the ones we’re interested in. For filtering only specific categories well need to join terms table. Then we have to find out which posts belong to those categories. That’s why we’ll join the wp_term_relationships table. And last but not least, we’ll throw posts table to the mix.

Let’s say we wanted to count all posts from “Advanced” and “Intermediate” categories. Assuming that table prefix is the default one, our SQL query should look something like:

SELECT	COUNT( DISTINCT cat_posts.ID ) AS post_count
FROM 	wp_term_taxonomy AS cat_term_taxonomy INNER JOIN wp_terms AS cat_terms ON
		cat_term_taxonomy.term_id = cat_terms.term_id
	INNER JOIN wp_term_relationships AS cat_term_relationships ON
		cat_term_taxonomy.term_taxonomy_id = cat_term_relationships.term_taxonomy_id
	INNER JOIN wp_posts AS cat_posts ON
		cat_term_relationships.object_id = cat_posts.ID
WHERE 	cat_posts.post_status = 'publish' AND
	cat_posts.post_type = 'post' AND
	cat_term_taxonomy.taxonomy = 'category' AND
	cat_terms.slug IN ('advanced', 'intermediate')

The name of the posts table is somewhat misleading because it contains not only posts but pages, post revisions, and whatnot… Hence the condition post_type = 'post'. Being picky like we are, we only want published posts so we expanded our condition with a little post_status = 'publish'.

Another thing I want to point out is the COUNT DISTINCT… A well know feature in Wordpress is that a post can belong to any number of categories so without counting only distinct post IDs we could end up with a wrong (much bigger) count.

Now we’ll change that query a bit and wrap it in a PHP function. That will allow us to pass any number of category slugs.

function wdd_in_category_count($catslugs = '', $display = true) {
	global $wpdb;

	$post_count = 0;
	$slug_where = '';
	$catslugs_arr = split(',', $catslugs);

 	foreach ($catslugs_arr as $catslugkey => $catslug) {
		if ( $catslugkey > 0 ) {
			$slug_where .= ', ';
		 }

 		$slug_where .= "'" . trim($catslug) . "'";
	}

	$slug_where = "cat_terms.slug IN (" . $slug_where . ")";

	$sql =	"SELECT	COUNT( DISTINCT cat_posts.ID ) AS post_count " .
		"FROM 	" . $wpdb->term_taxonomy . " AS cat_term_taxonomy INNER JOIN " . $wpdb->terms . " AS cat_terms ON " .
				"cat_term_taxonomy.term_id = cat_terms.term_id " .
			"INNER JOIN " . $wpdb->term_relationships . " AS cat_term_relationships ON " .
				"cat_term_taxonomy.term_taxonomy_id = cat_term_relationships.term_taxonomy_id " .
			"INNER JOIN " . $wpdb->posts . " AS cat_posts ON " .
				"cat_term_relationships.object_id = cat_posts.ID " .
		"WHERE 	cat_posts.post_status = 'publish' AND " .
			"cat_posts.post_type = 'post' AND " .
			"cat_term_taxonomy.taxonomy = 'category' AND " .
			$slug_where;

	$post_count = $wpdb->get_var($sql);

	if ( $display ) {
		echo $post_count;
	} 

	return $post_count; 

}

Our little function here has a $catslugs input parameter that expects category slugs in a string separated with commas. We also used $wpdb variables instead of hard coding the table names, witch is always a good practice.

How can you use it

Download Multiple category post counter function for Wordpress

First download the code, uncompress and paste it somewhere in your functions.php file. Then find the place in your template file where you want to display number of posts form certain categories and call the wdd_in_category_count() function.

For example, if you had a movie review blog and you wanted to display number of reviews for Horror and SF movies, put something like this:

<p>Total number of Horror and SF reviews: <?php wdd_in_category_count('sf, horror') ?>.</p>

And there you have it… That’s how you count sheep posts within multiple categories.

Please reply with your questions, comments and suggestions.

From day one, we also wanted to add a lot of features to the site. With v2, we’re finally introducing some of those new features. We’ll let you discover those, of which some are not obvious at first glance.

Design-wise, we’ve not gone far away from version one. What we hope we have done is spice things up a little bit, making the site more visually attractive. We’ve stuck to the familiar, neutral color scheme and the lovely Omnes typeface.

WebD&D is still running on WordPress, spiced with some custom made code to achieve exactly what we wanted. The most fun was writing some custom SQL queries for all tag-category combinations and getting variable number of posts (tips and blog) for any category combination. We plan to share the acquired knowledge and experience in future articles. So stay tuned.

We also used some of the sweet plugins available:

• WP Super Cache
• Yet Another Related Posts Plugin
• WP-PostRatings
• Twitter for Wordpress
• All in One SEO Pack

This time around, as far as JavaScripting goes, we really took advantage of the excellent jQuery framework with some cool plugins. In all our laziness we used:

• TableSorter
• ColorBox

We don’t want to keep you away from browsing the site a second longer. We hope you enjoy WebD&D v2. Let us know what you think in the comments.

Here are 15 tips on how to tweet politely and avoid getting unfollowed.

1. Provide your name, avatar and a short bio

Always include your name and a short bio in your Twitter profile. People want to know who you are. Do not hide behind false names. Be honest if you expect honesty. Make sure to use your photo or a custom avatar so others can remember and recognize you.

2. Be social

Be social and interact. Make your tweets personal and let your followers get to know you. Kindly reply if someone asks you a question. Feel free to ask questions zourself and connect with people. Share interesting links with the community (but be sure to check they actually work). After all, Twitter is a social network.

3. Be moderate in self-plugging

There’s nothing wrong with the occasional self-plug, but don’t keep a Twitter account just to promote your work. Although many people use Twitter simply to publish site news, that is not what Twitter is about.

4. No auto direct messages, please

Auto direct messages are a big no-no, even if you are just being nice and saying hi to someone who has just started following you. What auto messages are really saying is “I don’t have the time to be really polite so I’ll just send and auto DM to everyone”. Also, no one is expecting a DM when they start following you.

5. Give credit

When you find a useful information somewhere, be it a tweet, a blog post or a picture you want to share, give credit by letting people know who it was that led you to your discovery. If you read a tweet you want to share with others, a simple retweet will do.

6. Don’t use twitter for chatting or personal conversation

Twitter is not an instant messenger. Not only it is not as effective as IM is, but others don’t really want to read through multiple tweets of your personal conversation. Instead of making private conversations public, use direct messages (or e-mail or an IM client).

7. Your post should not span through multiple tweets

A tweet should contain up to 140 characters. That’s 140, and not a character more. Don’t write messages that are more than one tweet long and continue your message in the next tweet. Move longer posts to appropriate mediums, like Posterous, Tumblr, or your blog.

8. Don’t tweet too much

Twitter is all about quick and easy messages. Try not to tweet too much or your followers might not want to read all what you have to say. For me, reading dozens of tweets and retweets a day from a single person is too much. Choose quality over quantity. If you suspect you might be tweeting too much, a good idea might be to ask your followers what they think.

9. Don’t flood

While there are people who are interested in reading dozens of your tweets one after the other, most are not. Flooding is not polite so try not to overdo it. If your followers have too much to read and explore, they might easily choose to ignore your tweets.

10. Follow, unfollow and block whoever you wish

On Twitter, you are free to follow and unfollow whoever you wish. You’re also free to block people from viewing your tweets. When someone follows you, you are not obligated to follow them back. When someone unfollows you, it does not mean you have to unfollow them. Unfollowing someone does not mean “I don’t like you”.

11. Do not follow everyone who follows you

Do not follow everyone who follows you, just for the sake of it. What good is it to follow thousands of people if you aren’t really following their tweets? Most users who follow thousands of people are considered to be spammers.

12. Use hashtags, but do not overuse them

Hashtags aren’t really effective if every word in a tweet is a hashtag. Use them sparingly to help people find information without making the message look spammy.

13. Do not spam

Never spam on Twitter and do not send people unwanted information. People will unfollow you if you keep asking them to retweet your posts, help you reach a certain number of followers or if you are retweeting contest tweets all of the time. Open a second Twitter account if you like the contests that require retweeting.

14. Provide enough information

When you tweet, make sure you provide enough information. Simply copy/pasting an URL is not enough. Add value to your tweets and make them easy to understand and scan.

15. Retweet in 140 characters

Sometimes a retweet will not fit inside the 140 chars limit once you add the @username. To make it fit, cut the last part of the message. If you think it will not make a lot of sense like that, change the text but try to keep it as similar to the original as possible. What you are basically doing is quoting someone else, so be fair.

A 12 month subscription to CushyCMS Pro, worth over $330, goes to Spain and Jose Vittone! Congratulations to Jose and thanks to Leigh from Stateless Systems.

Thanks to all the participants, stay tuned for more giveaways on WebD&D.

To enter our contest, all you need to do is:

1. Post a comment in this post, answering Why would a free 12 month CushyCMS Pro subscription be cool?
2. Tweet the CushyCMS giveaway

The giveaway is open until August 10, 2009. We’ll be chosing the lucky winner with a random generator on August 11 after which Leigh from Stateless Systems will be providing you with the licence. Best of luck to all of you.

More giveaways will follow so be sure to follow us on Twitter.

On our blog, we’ll be covering all web design and development related topics. Of course, we’re also open to any of the suggestions you may have. What would you want us to write about? How would you make our site better? What features would you like to see? As always, you are more than welcome to comment on our site and make your voice count.

We also have a giveaway ready for all our readers, so stay tuned and enter the competition soon.

Last, but not least, we’d like to thank our sponsor, WPWebHost, because it’s the sponsors that keep WebD&D alive.