Fetch all rows related to user - php

Question

I am trying to create a json object with data from two tables.
Table 1 holds user information
id
name
username
email
Table 2 holds messages to the users
id
f_id
message
date
So far so good. I have managed to do this with LEFT JOIN
$sql = "SELECT * FROM user LEFT JOIN messages ON user.id = messages.f_id
$result = mysqli_query($conn, $sql) or die(mysql_error());
while ($data = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
$messages[] = array(
'users' => array(
'Id' => $data['id'],
'Name' => $data['name'],
'Username' => $data['username'],
'Email' => $data['email'],
),
'messages' => array(
'f_id' => $data['f_id'],
'message' => $data['message'],
'date' => $data['date'],
);
);
}
but the issue/challenge is that it only returns one row from messages table even if there multiple rows related to the user.
This is what I'm trying to achieve
'user' => array(
'id' => 1,
'name' => John Doe,
'username' => Johndoe,
'email' => johndoe#mail.com,
),
'messages' => array(
'id' => 1,
'f_id' => 1,
'message' => 'Just a test',
'date' => 14-08-2014,
'id' => 2,
'f_id' => 1,
'message' => 'Just a test 1',
'date' => 12-08-2014,
);
How can I achieve this?
Do I need to run a while in while?

Answer 1

You can do it in 2 ways:
1) Query only the users, and then iterate over them and query the messages for each user. That means that you will query the database N+1 times, where N is the number of users.
2) Query the messages joined with the users (and not the opposite), which will result with a lot of "unused" data, but a single query.

Answer 2

Try:
SELECT
user.id AS user_id, user.name, user.email, user.username,
messages.id AS message_id, messages.f_id, messages.message, messages.date
FROM user, messages
LEFT JOIN messages ON user.id = messages.f_id
Note that an alias was needed for user.id and messages.id as both column names are the same.

Answer 3

Please update your sql query
$sql = "SELECT * FROM user Right JOIN messages ON user.id = messages.f_id
or
$sql = "SELECT * FROM messages LEFT JOIN user ON user.id = messages.f_id

Answer 4

You can try that :
SELECT * FROM messages LEFT JOIN user ON user.id = messages.f_id
It will get all messages with users but if a user has no messages, you'll not be able to get it with this kind of query.

Answer 5

What is probably happening is that when you're running the query on the users table, it will use the primary key of that table to ensure that there's no "duplicate" data (as it should). You have two options here:
Query Users, Query Messages [Not Recommended]
This might be a little slow since you'll be querying the database many times. You could do something like
SELECT * FROM users;
then later iterate over the users result and run a query on messages
SELECT * FROM messages WHERE f_id = <user_id>;
What's the issue with this? The more users you have, the more wasteful this is, and also the slower your site will perform. Not recommended.
Query messages, join users [Recommended]
Run this query on messages, rather than users. It will use the primary key of the messages table (which will be id) to determine what is a duplicate or not.
SELECT * FROM messages LEFT JOIN users ON users.id = messages.f_id;
This is much more efficient because it's using one query to grab all the data you need and it should need a little tweaking maybe as your site grows.