mysql liking you and others [closed] - php

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I wonder how to do this
I mean the "You and 19,389 others" How do you identify YOU from others. If a user is logged in and like a status or favorite a status or something like facebook. I wanna catch the "you" part. But I don't seemed to understand the logic behind it.
I'm using php, and jquery. How do you sort this out in sql? or is it really sql? how do you define the user from others?
If I'm doing it the wrong way or asking it the wrong way, please tell me the right way and the answer guys I badly need your help.

Answer 1

With only one query you can do like this:
SELECT COUNT(user_id) AS everybody, SUM(user_id = "your_user_id") AS you FROM fb_likes WHERE post_id = 4;
Then if you is bigger than zero print (in fact it must be 0 or 1 only):
You and [everybody - you] others like this.
Else
[everybody] like this.

Answer 2

First of all, when you click on "Like" there's an entry going inside a database assigned to the post. So let's say the post has ID 1234567890 so you going to see something like that inside your database table :
PostID UserID
1234567890 54543534
1234567890 75231415
1234567890 78653421
1234567890 99653221
// Query example
SELECT COUNT(*) FROM LikeTable WHERE PostID = 1234567890
// Return 4
First of all you count all like, there's 4 here.
After, you check if the UserID of the current logged user is in the database.
Yes. He liked.
No, he didn't liked.
Let's say we are user 54543534. I am in the database so I liked the post.
// Query example
SELECT PostID FROM LikeTable WHERE PostID = 1234567890 AND UserID = 54543534 LIMIT 1
// Return 1
Let's say we are user 8748977777. I am NOT in the database so I didn't liked the post.
// Query example
SELECT PostID FROM LikeTable WHERE PostID = 1234567890 AND UserID = 8748977777 LIMIT 1
// Return 0
So I say the IF/ELSE statement would be :
IF I liked
You and COUNT - 1 others like this.
ELSE
COUNT like this. Click to like.
EDIT :
I think something like that will make the job :
SELECT COUNT(PostID) AS All, SUM(UserID = X) AS Liked FROM LikedTable WHERE PostID = X

Answer 3

Query for others:
SELECT COUNT(userid) FROM likeTable WHERE postid = $postid
Query for you:
SELECT COUNT(userid) FROM likeTable WHERE postid = $postid AND userid = $_SESSION['userid']
Then do:
if ($youCount == 1) {
echo "Liked by you and " . $othersCount - 1 . " others";
}
else {
echo "Liked by $othersCount people";
}

Answer 4

I don't know much about optimal database schemas, but the way I see this is that every single like in Facebook terms is a node on FB's social object graph. Which probably means that every single like is an individual database record on some table. To count the number of likes, you just do a COUNT on like records associated with a post.
Now if that's the case, then it's trivial to include some identifying information on the like record on who performed it. Top-of-head, it would be an FK on a user's PK.
So if you're logged in on Facebook, it knows who you are and what your associated user ID is. For every post that it aggregates the likes to, it can counter-check your user ID to the user ID FKs on the likes, and determine which of those posts you've actually liked. Hence, it can conditionally display either You and 14,000 others like this or 14,001 like this.

Answer 5

Struggling to understand the question but I think you might be trying to do too much in one go.
Either Run two queries, one to check if 'you' (your session id etc.) are in the table that records this or pull the whole lot and use in_array or something similar to see if 'you' are in the list.