如何添加另一个条件pdo sql语句

i found in the internet this and so far so good with one condition!! but how can i add 2 or more conditions in the sql statement??

public static function getInstance() {
    if(!isset(self::$_instance)) {
        self::$_instance = new DB();
    }
    return self::$_instance;
}

public function query($sql, $params = array()) {
    $this->_error = false;

    if($this->_query = $this->_pdo->prepare($sql)) {
        $x = 1;
        if(count($params)) {
            foreach($params as $param) {
                $this->_query->bindValue($x, $param);
                $x++;
            }
        }

        if($this->_query->execute()) {
            $this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ);
            $this->_count = $this->_query->rowCount();
        } else {
            $this->_error = true;
        }
    }

    return $this;
}

public function action($action, $table, $where = array()) {
    if(count($where) === 3) {
        $operators = array('=', '>', '<', '>=', '<=');

        $field = $where[0];
        $operator = $where[1];
        $value = $where[2];

        if(in_array($operator, $operators)) {
            $sql = "{$action} FROM {$table} WHERE {$field} {$operator} ?";

            if(!$this->query($sql, array($value))->error()) {
                return $this;
            }
        }

    }

    return false;
}

public function get($table, $where) {
    return $this->action('SELECT *', $table, $where);
}

i was thinking to create another function like this:

public function get($table, $where1, $where2) {
    return $this->action('SELECT *', $table, $where, $where2);
}

the conditions are $where and $where2 etc... how can i do this?? im aware that i should create new methods action2 and query2 to implement the changes but as i said im trying 5 days now and i tried everything. plz help me and thanks in advance!!

i found the solution but i had to reduce safety.. i only changed this!

public function action3($action, $table, $where = array()) {
    /*if(count($where) === 6 ) {*/
        $operators = array('=', '>', '<', '>=', '<=');
        $field1 = $where[0];
        $operator1 = $where[1];
        $value1 = $where[2];
        $field2 = $where[3];
        $operator2 = $where[4];
        $value2 = $where[5];

/*if(in_array($operator, $operators)) {*/ $sql = "{$action} FROM {$table} WHERE {$field1} {$operator1} {$value1} AND {$field2} {$operator2} {$value2}"; if(!$this->query($sql, array($value1, $value2))->error()) {

                return $this;
            }
     /*   }*/

   /* }*/

    return false;
}

public function get3($table, $where) {
    return $this->action3('SELECT *', $table, $where);
}