How to make a manual 'like' function (like facebook) using MySQL - php

Question

I am using MySQL and cPANEL for making my website. I'm having a problem in figuring out how to make manual likes function (Facebook like button, or YouTube thumbs up button).
Am I going in the right way to make a "like" button in my website?
VIDEOTABLE:
+----+----------+-----------+
| ID | VIDEO URL| LIKES |
+----+----------+-----------+
| 1 | example 1| 5774 |
| 2 | example 2| 9654 |
| 3 | example 3| 1254 |
| 4 | example 4| 7656 |
| 5 | example 5| 6757 |
| 6 | example 6| 5675 |
| 7 | example 7| 4565 |
+----+----------+-----------+
ID is my serial
VIDEO_URL is my page link or the video link
likes is the users liking this
So, to like the video when USER will clicks the like button without login it will redirect and show the login panel. Then, user will login into it via FACEBOOK or TWITTER so the site can get the USER_ID
Ones the user logins there likes option their will be this code (NOT SURE)
SQL> UPDATE VIDEOTABLE
SET ID = '3', LIKES = ????;
How can i increase +1 value in the table? And then when the USER likes it, the site refreshes and shows the latest value (by increasing by +1).
My Second Problem = How can i restrict the user by giving only one chance to increase the like) and to undo Rollback Query.

Answer 1

You should be able to use the following:
UPDATE VIDEOTABLE SET LIKES=LIKES+1 WHERE ID=3;
However, it may be wise to set a separate lookup table that indicates whether a particular user has already 'liked' something, so that they may not 'like' it more than once.
That table would look like this:
tblLikesLookup
+----+--------+--------+
| ID | videoID| userID |
+----+--------+--------+
| 1 | 1 | 10 |
| 2 | 3 | 7 |
| 3 | 2 | 10 |
| 4 | 8 | 8 |
| 5 | 6 | 8 |
+----+--------+--------+
You could even use this table in place of your VIDEOTABLE to store your likes. To get the number of likes for any given video,
SELECT COUNT(*) FROM tblLikesLookup WHERE videoID=[videoID];
or for all videos,
SELECT COUNT(*) FROM tblLikesLookup GROUP BY videoID;
This may eventually become slow as the volume to your site increases, in which case using a separate counter like the one you have above will come in handy.

Answer 2

if i understand you right,
you can simple increase any number like that:
update VIDEOTABLE set LIKES = LIKES + 1 where ID = ...
so as the same to reduce likes
update VIDEOTABLE set LIKES = LIKES - 1 where ID = ...
it is not important what the user id is. You need video ID
EDIT:
if you want to prevent multiple likes, you need a new table too.
TABLE: USER_TO_LIKES
id | user_id | video_id
so you must firstly check if user liked it before:
$c = mysql_num_rows(mysql_query("select id from USER_TO_LIKES where video_id = 11 and user_id = XX"));
if($c == 0){
mysql_query("update VIDEOTABLE set LIKES = LIKES + 1 where ID = 11 ");
mysql_query("insert into USER_TO_LIKES set video_id = 11, user_id = XX");
}
If unlike:
$c = mysql_num_rows(mysql_query("select id from USER_TO_LIKES where video_id = 11 and user_id = xx"));
if($c > 0)
{
mysql_query("update VIDEOTABLE set LIKES = LIKES - 1 where ID = 11");
mysql_query("delete from USER_TO_LIKES where video_id = 11 and user_id = XX");
}
thats it.
EDIT2: see above

Answer 3

You Will Need the video id And The User That has clicked And Another Table(Called Liked_People) For People Who Has Already Liked Something like that:
+-------+---------+
|UserId |VideoId |
+-------+---------+
|1 |5739 |
+-------+---------+
Now Wen The User Click On Like Send An XMLHTTP request to that PHP function:
function Like($usrid , $vidid){
//usrid = userid And vidid = video id
$Comm1 = $Con->prepare("SELECT * FROM Liked_People WHERE UserId = ? And VideoId = ?");
$Comm1->execute(Array($usrid , $vidid);
if($Comm1->rowCount() == 0){
$Comm2 = $Con->prepare("INSERT INTO Liked_People (UserId , VideoId) VALUES (?,?)");
$Comm2->execute(Array($usrid , $vidid));
$Comm3 = $Con->prepare("SELECT Likes FROM VideoTable WHERE Id = ?");
$result = $Comm3->Execute(Array($vidid));
$final = $result + 1;
$Comm4 = $Con->prepare("UPDATE VideoTable SET Likes=? WHERE ID = ?");
$Comm4->Execute(Array($final , $vidid));
}else { return false;}
}
And That is but if you want to get A list of the usernames that has liked lets say that you have the People Table Like That:
+-------+--------------+
|Id |Username |
+-------+--------------+
|1 |Ahmad Mehmet |
+-------+--------------+
And This is the Code:
function get_likers($vidid){
if($vidid == null or $vidid == "" or $vidid == 0){
return false;
}
$Comm1 = $Con->prepare(SELECT UserId FROM Liked_People WHERE VideoId = ?);
$Comm1->Execute(Array($vidid));
$arr = $Comm1->fetchAll();
$finale = Array();
$i = 0;
foreach($arr as $row){
$Comm = $Con->Prepare("SElECT Username WHERE Id = ?");
$finale[$i] = $Conm->Execute(Array($row[0]));
$i++;
}
return $finale
}
This function is just for backups and Not essential.
function Work_Array($Arr){
echo '<table border="2">';
echo '<tr><th>Users That Has Liked</th></tr>';
foreach($Arr as $el){
echo"<tr><td>";
echo $el;
echo "</td></tr>";
}
echo "</table>";
}
Called Like That:
work_array(get_likers($vidid));
Questions?:D