insert_id mysqli - mysqli

Question

I'm trying to return the inserted id from a mysql INSERT query. Each time I run the function I get 0 as the result. Can someone please explain at what point I can retrieve the value because although the script below executes I cannot retireve the inserted id. Probably done something stupid.
<?php
public function execSQL($sql, $params, $close){
$mysqli = new mysqli(DB_HOST,DB_USER,DB_PASSWORD,DB_NAME);
$stmt = $mysqli->prepare($sql) or die ("Failed to prepared the statement!");
call_user_func_array(array($stmt, 'bind_param'), $this->refValues($params));
$this->insert_id($this->connection);
$stmt->execute();
if($close){
$result = $mysqli->affected_rows;
} else {
$meta = $stmt->result_metadata();
while ( $field = $meta->fetch_field() ) {
$parameters[] = &$row[$field->name];
}
call_user_func_array(array($stmt, 'bind_result'), $this->refValues($parameters));
while ( $stmt->fetch() ) {
$x = array();
foreach( $row as $key => $val ) {
$x[$key] = $val;
}
$results[] = $x;
}
$result = $results;
}
$stmt->close();
$mysqli->close();
return $result;
}
?>

Answer 1

Check $mysqli->insert_id after executing insert query.