WordPress class wpdb

Instanciovaná třída wpdb může komunikovat s libovolným počtem tabulek, ale pouze s jednou databází současně. Ve vzácných případech, kdy se potřebujete připojit k jiné databázi, vytvořte instanci vlastního objektu ze třídy wpdb s informacemi o připojení k vlastní databázi.

Více informací na developer.wordpress.org

Pěkný tutoriál na envanto

//grab the WPDB database object, using WP's database
//more info: http://codex.wordpress.org/Class_Reference/wpdb
global $wpdb;

//make a new DB object using a different database
//$mydb = new wpdb('username','password','database','localhost');

//basic functionality

//run any query
$wpdb->query( "SELECT * FROM wp_posts" );

//run a query and get the results as an associative array
$wpdb->get_results( "SELECT * FROM wp_posts" );

//get a single variable
$wpdb->get_var( "SELECT post_title FROM wp_posts WHERE ID = 1" );

//get a row as an assoc. array
$wpdb->get_row( "SELECT * FROM wp_posts WHERE ID = 1" );

//get an entire column
$wpdb->get_col( "SELECT post_title FROM wp_posts" );

//insert data into a table… sql protection?
$wpdb->insert( 'wp_posts', array( 'post_title' => 'test', 'ID' => 5 ), array( '%s', '%d') );

//update an existing row
$wpdb->update( 'wp_posts', array( 'post_title' => 'test2'), array( 'ID' => 5 ), array( '%s' ) );

//escaping queries
$wpdb->query( $wpdb->prepare( "UPDATE INTO wp_posts set post_title = %s WHERE ID = %d", 'test2', 5 ) );

//two steps to insert a post…

//define the post… all field optional
$post = array( 
		'post_title' => 'test',
		'post_type' => 'station',
		'post_status' => 'publish',
		'post_author' => 'greg',
);

//insert
$id = wp_insert_post( $post );

//store key/value pair
update_post_meta( $id, 'expiration', '201101010' );

//retrieve key/value pair
$meta = get_post_meta( $id, 'expiration', true );

//search for posts by key/value pair
$posts = get_posts( 'expiration=20110110' );

//associate taxonomy terms with a post
wp_set_post_terms( $id, array( 'red', 'blue', 'green'), 'colors' );

//query posts by taxonomy term
$posts = get_posts( 'color=red' );

//wizards for creating taxonomy / post types
//will output a plugin that you just drop into /wp-content/plugins and activate
//http://themergency.com/generators/wordpress-custom-taxonomy/
//http://themergency.com/generators/wordpress-custom-post-types/

//Cache

//store a value in cache
wp_cache_set( 'unique_key', $data );

//retrieve value from cache
$data = wp_cache_get( 'unqiue_key' );

/* additional things to do
1) Install W3 Total Cache to get DB and object caching
2) Use the front end / admin UI to browse / sort data
*/