jquery - php - Enabling users to favorite posts -

on website want allow users favorite posts. logged in user directed page shows posts , under each 1 placed hyperlink favorite. want text change favorite favorited , other way around. how do that?

html , php

<?php session_start(); require_once('connection.php');  mysql_select_db($database_connection, $connection); $query_favorite = "select username, post_id favorite"; $favorite = mysql_query($query_favorite, $connection) or die(mysql_error()); $row_favorite = mysql_fetch_assoc($favorite); $totalrows_favorite = mysql_num_rows($favorite); ?>  <a href="#" class="favourite">favourite</a> 

tables in datatbase

create table `user` (   `username` varchar(45) not null,   `email` varchar(45) not null,   `password` varchar(45) not null,   `profilepic` varchar(50) default null,   primary key (`username`) ) engine=innodb default charset=utf8  create table `post` (   `post_id` int(11) not null auto_increment,   `title` varchar(100) not null,   `dato` date not null,   `category` varchar(100) not null,   `description` varchar(500) not null,   `text` longtext not null,   primary key (`post_id`), ) engine=innodb auto_increment=10 default charset=utf8  create table `favorite` (   `username` varchar(45) not null,   `post_id` int(11) not null,   primary key (`username`,`post_id`),   key `fk_favorite_post1_idx` (`post_id`),   constraint `fk_favorite_user` foreign key (`username`) references `user` (`username`) on delete no action on update no action,   constraint `fk_favorite_post1` foreign key (`post_id`) references `post` (`post_id`) on delete no action on update no action ) engine=innodb default charset=utf8 

php

<?php session_start(); require_once('connection.php');  mysql_select_db($database_connection, $connection); $query_favorite = "select username, post_id favorite"; $favorite = mysql_query($query_favorite, $connection) or die(mysql_error()); $row_favorite = mysql_fetch_assoc($favorite); $totalrows_favorite = mysql_num_rows($favorite);  if(in_array($_post['id'], $row_favorite)) {    //is favourited, run query remove row db, won't favorited anymore  } else {    //post not favourited already, run query add new favourite db. }  ?> 

html

<a href="#" class="favourite" data-id="<?php echo $post_id; ?>">favourite</a> 

jquery

$(document).ready(function() {     $('.favourite').on('click', null, function() {         var _this = $(this);         var post_id = _this.data('id');         $.ajax({           type     : 'post',           url      : '/file.php',           datatype : 'json',           data     : 'id='+ post_id,           complete : function(data) {                if(_this.siblings('.typcn-star-outline'))                {                  _this.html('<span class="typcn typcn-star-full-outline"></span>favourite');                }                else                {                  _this.html('<span class="typcn typcn-star-outline"></span>favourited');                }             }         });     }); }); 

also, please note in php mysql_* functions have been deprecated , unsafe use (they allow sql injection attacks). learn more pdo here: http://code.tutsplus.com/tutorials/why-you-should-be-using-phps-pdo-for-database-access--net-12059