通过+1更新mysql中的自动增量列？

Question

Can someone please help me, I am trying to create a users like system. Users should be able to click A like button and have it insert the user_id of that profile and auto increment the likes column. I'm also trying to make it so that the next person who comes along and likes the same profile, can also hit like and update the likes auto increment column by one each time.

I am new to mysql and php and i'm really struggling with this. Could someone please show me where i'm going wrong? Thanks in advance.

<?php

require_once('includes/session.php');
require_once('includes/functions.php');
require('includes/_config/connection.php');

session_start();

    confirm_logged_in();

    if (isset ($_GET['to'])) {
    $user_to_id = $_GET['to'];


}


if (!isset($_GET['to']))
    exit('No user specified.');

$user_id = $_GET['to'];


$result = mysql_query("SELECT * FROM ptb_likes WHERE liked_id ='".$user_to_id."' ");

if( mysql_num_rows($result) > 0) {
    mysql_query("UPDATE ptb_likes SET likes +1 WHERE liked_id = '".$user_to_id."' ");


    $autoinc = mysql_query("ALTER TABLE likes AUTO_INCREMENT = $id");
}
else
{
    mysql_query("INSERT INTO ptb_likes (liked_id) VALUES ('".$user_to_id."') ");
}



if($result) 
{ 

header("Location: {$_SERVER['HTTP_REFERER']}");

}
?>

Answer 1

If you're doing a "Like"-wise system, it's preferable to have a table with the likes one per row.

THen you can query the DB searching by reference ID.

Let's you have posts, and likes. Each post has a Post_ID, so your likes table schema would be something like

ID
Post_ID
Time

So next time you want to see how many likes does Post #3 has, you do

SELECT COUNT(*) FROM posts WHERE post_id = 3

That way you have better control and reduce queries.

Incrementing the value of likes in a single row, would be done, but not efficient.