Question

I am trying to create a wall post script like facebook

In the newsfeed area it should display posts from current user and friends.

I am using three tables:

1. Users:
   userid, username, fname, lname, sex, email.

2. posts:
   post_id, username, posted_by, title, type.

3. friends:
   Id, user1, user2.

When any user adds another user both will be added to the friends table.

I am using mysql view to create a temporary table to store all friends of current user with this statement:

$friends = "CREATE VIEW ".mysql_real_escape_string($_SESSION['username'])." AS 
    SELECT users.username "."FROM users, friends "."
    WHERE ((users.username = friends.user1 OR users.username = friends.user2) AND 
    (users.username != '".mysql_real_escape_string($_SESSION['username'])."')) AND 
    (friends.user1 = '".mysql_real_escape_string($_SESSION['username'])."' OR 
    friends.user2 = '".mysql_real_escape_string($_SESSION['username'])."')";

mysql_query($friends) or die(mysql_error());

I am using below statement to display posts on page:

$query = "SELECT posts.*, user.fname, user.lname, user.username "."FROM 
    posts, users, ".mysql_real_escape_string($_SESSION['username'])." "."
    WHERE 
    (users.username = ".mysql_real_escape_string($_SESSION['username']) ".username 
    AND users.username = posts.username) OR 
    (users.username = '".mysql_real_escape_string($_SESSION['username'])."' AND 
    users.username = posts.username) 
    ORDER BY posts.post_id DESC LIMIT 0, 11";

The problem is, it displays friends posts without any issue; but posts from the current users are repeated, once for each friend.

In other words, if I have 5 friends then each of my posts will be displayed 5 times.

Please let me know what’s wrong with this query and post me if there is any better way to do this.

Answer 1

You need to use the MySQL GROUP BY Aggregate:

$query = "SELECT posts.*, user.fname, user.lname, user.username "."
    FROM posts, users, ".mysql_real_escape_string($_SESSION['username'])." "."
    WHERE (users.username = ".mysql_real_escape_string($_SESSION['username']) ".username  
    AND users.username = posts.username)
    OR (users.username = '".mysql_real_escape_string($_SESSION['username'])."' AND 
    users.username = posts.username) 
    GROUP BY posts.post_id
    ORDER BY posts.post_id DESC
    LIMIT 0, 11";`

This will group a post into 1 row based on post_id.