/**
* Usage: Rename the function and add your own $sql 
*/
 
function test_function(){
	global $wpdb; 
 
//check if there is some past cached results
	$result = wp_cache_get(date('Y-m-d'), __FUNCTION__);	
 
        //if there wasn't a cached result, run your query
	if($result === false) 
	{
               //place your SQL here
		$sql = "SELECT p.post_author 
					FROM $wpdb->posts p 
					WHERE p.post_status = 'publish' 
					AND p.post_type = 'business' "; 
 
		$result = $wpdb->get_col($sql);
 
                //once the query has been run, cache the results
		wp_cache_add(date('Y-m-d'), $result,  __FUNCTION__);
	}
	return $result;	
}