Control which posts show up in The Loop with the WordPress query_posts() function.
It accepts a variety of parameters in the same format as used in your URL. (e.g. p=1 to show only post of ID number 1)
Place a call to query_posts() in one of your Template files before The Loop begins. The wp_query object will generate a new SQL query using your parameters.
WordPress then ignores the other parameters it received via the URL (such as page number or category).
Why go through all the trouble of changing the query that was meticulously created from your given URL?
You can customize the presentation of your blog entries by combining it with page logic (like the Conditional Tags) - all without changing any of the URLs.
Common uses might be to
This is not an exhaustive list yet. It is meant to show some of the more common things possible with setting your own queries.
Show posts only belonging to certain categories.
Show One Category by ID
Display posts from only one category ID:
query_posts('cat=1');
Show One Category by Name
Display posts from only one category by name:
query_posts('category_name=Staff Home');
Exclude Posts Belonging to Only One Category
Show all posts except those from a category by prefixing its ID with a '-' (minus) sign.
query_posts('cat=-3');
This excludes all the posts that belong only to category 1. There is a proviso however: it will exclude all the posts that belong only to category 1. If a post belongs to another category as well, it will still be picked up.
You can also restrict the posts by author.
author_name operates on the user_nicename field, whilst author operates on the author id.
Retrieve a single post or page.
As a consequence of the Template Hierarchy, home.php executes first. This means that you can write a home.php which calls query_post() to retrieve a particular page and set that to be your front page. Without any plugins or hacks, you’ve got a mechanism to run, show and maintain a non-bloggy front page.
More useful perhaps would be to take advantage of WP’s new Page functionality and use that for you front page. You could set your "about page" to be the entry point or maybe your site's colophon. You might even do something a bit more dynamic and set a custom page that shows a list of the latest comments, posts, categories and archives. See the example below.
Changes the ordering of the list. This can be handy when making page templates, such as indexes. Note the distinction between "orderby" and "order".
Retrieve posts belonging to a certain time period.
These deal a listing of posts broken up over multiple pages, not with the parameter.
Placing this code in your index.php file will cause your home page to display posts from all categories except category ID 3.
<?php
if (is_home()) {
query_posts("cat=-3");
}
?>
To retrieve a particular page, you could use the following:
<?php
query_posts('page_id=7'); //retrieves page 7 only
?>
or
<?php
query_posts('pagename=about'); //retrieves the about page only
?>