Get error number with oracle

[eluser]Unknown[/eluser]
Hi!

First of all sorry for my bad English..

I have this function in a model:

Code:

function insertUser($data){

    $sql = "INSERT INTO USERS VALUES (?, ?, ?, ?, ?, ?, ?, ?)";

    $query = $this->db->query($sql, array(
        $data["uname"],
        $data["nome"],
        $data["dnuser"],
        $data["muser"],
        $data["fruser"],
        $data["cpuser"],
        $data["euser"],
        md5($data["passu"])
      ));

    //return $this->db->_error_number();

}

I have one primary key and when data is correct the function works but when is inserted a duplicate key the function doesn't work. But how can i know that? i mean how can i catch the error ORA-00001 ??

BTW the commented line doesn't work..

Thank you very much!!