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();