Modify WordPress Query query

modify_query.php

<?php
// With dual parameters
function modify_query_one( $clauses, $query ) {
	global $wpdb;
	if ( isset( $query->query['orderby'] ) && 'color' == $query->query['orderby'] ) {

		$clauses['join'] .= <<<SQL
LEFT OUTER JOIN {$wpdb->term_relationships} ON {$wpdb->posts}.ID={$wpdb->term_relationships}.object_id
LEFT OUTER JOIN {$wpdb->term_taxonomy} USING (term_taxonomy_id)
LEFT OUTER JOIN {$wpdb->terms} USING (term_id)
SQL;
		
		$clauses['where'] .= " AND (taxonomy = 'color' OR taxonomy IS NULL)";
		$clauses['groupby'] = "object_id";
		$clauses['orderby']  = "GROUP_CONCAT({$wpdb->terms}.name ORDER BY name ASC) ";
		$clauses['orderby'] .= ( 'ASC' == strtoupper( $query->get('order') ) ) ? 'ASC' : 'DESC';
	}

	return $clauses;
}
add_filter( 'posts_clauses', 'modify_query_one', 10, 2 );

// With single parameters
function modify_query_two( $pieces )
{
	global $wpdb;
	if( !is_user_logged_in() )

		// Either
		$pieces['where'] = str_replace( 
			"post_status = 'publish')", 
			"post_status = 'publish' OR $wpdb->posts.post_status = 'private') ",
			$pieces['where']
		);
		
		// Or
		$where_old = $pieces['where'];
		$where_new = $where_old." HAVING distance < $this->distance";
		$pieces['where'] = $where_new;

	return $pieces;
}
add_filter( 'posts_clauses', 'modify_query_two' );

// Print query output
function intercept_query_clauses( $pieces )
{
	echo '<style>#post-clauses-dump { display: block; background-color: #777; color: #fff; white-space: pre-line; }</style>';
	// >>>> Inspect & Debug the Query 
	// NEVER EVER show this to anyone other than an admin user - unless you're in your local installation
	if ( current_user_can( 'manage_options' ) )
	{
		$dump = var_export( $pieces, true );
		// echo "<PRE id='post-clauses-dump'>{$dump}</PRE>";
		echo '<pre id="post-clauses-dump">';
		print_r($pieces);
		echo '</pre>';
	}

	return $pieces;
}
add_filter( 'posts_clauses', 'intercept_query_clauses', 20, 1 );
?>