PHP implements the principle of chain operation

There are multiple methods in a class. When you instantiate this class and call the methods, you can only call them one by one, similar to:

db.php

<?php<br /><br />class db<br />{<br />    public function where()<br />    {<br />        //code here<br />    }<br />    public function order()<br />    {<br />        //code here<br />    }<br />    public function limit()<br />    {<br />        //code here<br />    }<br />}

index.php

<?php<br /><br />$db = new db();<br /><br />$db->where();<br>$db->order();<br>$db->limit();

If you want to implement chained calls, just add return $this at the end of the method.

db.php

<?php<br /><br />class db<br />{<br />    public function where()<br />    {<br />        //code here<br />        return $this;<br />    }<br />    public function order()<br />    {<br />        //code here<br />        return $this;<br />    }<br />    public function limit()<br />    {<br />        //code here<br />        return $this;<br />    }<br />}

index.php

<?php<br /><br />$db = new db();<br /><br />$db->where()->order()->limit();