$db is not available within the function scope, you could
Pass $db as an argument
function func($db, $query, $params){
return $db->db_control($query, $params);
}
$results = func($db, $query, $params);
Or
function func($query, $params){
global $db;
return $db->db_control($query, $params);
}
$result = func($query, $params);
Use global to make it available within the function, there’s probably other solutions too!
1
solved Accessing another class’ method from within a standalone function [closed]