How can a beginner in PHP improve their skills and understanding of database queries for Wordpress?

To improve skills and understanding of database queries for WordPress, a beginner in PHP can start by studying the WordPress Codex documentation on WP_Query and SQL queries. They can also practice creating custom queries using functions like $wpdb->get_results() and $wpdb->prepare(). Additionally, working on small projects or plugins that involve interacting with the WordPress database can provide hands-on experience and help solidify their understanding.

global $wpdb;

// Example query to retrieve posts from a specific category
$category_id = 1;
$query = "SELECT * FROM $wpdb->posts WHERE post_type = 'post' AND post_status = 'publish' AND ID IN (SELECT object_id FROM $wpdb->term_relationships WHERE term_taxonomy_id = $category_id)";
$posts = $wpdb->get_results($query);

foreach ($posts as $post) {
    // Output post data
    echo $post->post_title;
}