How to get 1 row per user with INNER JOIN - php

Question

I have two tables one is user and another is images. I gave users the option to select multiple images. I can store multiple images with same user_id in database, but when I am trying to get one image from every user I am getting all the images.
My query is something like this:
$query = "
SELECT *
FROM images i
JOIN users u
ON u.user_id = i.user_id
LIMIT 1";
When I run this query in while() loop, I only get very first image from images table.
I am really sorry if I am not able to clarify what I am try to ask.

Answer 1

Have you tried something like this:
SELECT * FROM users u INNER JOIN images i ON u.user_id = i.user_id GROUP BY u.user_id;
This should return you only one record from user/image tables for each user that has an image.
Don't run queries in a while loop. Instead, use one query to get all the desired records.
If you insist on running your query in a loop, then you are missing WHERE users.user_id = ? part in your query, so you can get a different result for each user in a loop.

Answer 2

you can do this without using join. simple select user and fetch data and on the bases of 'id' add query to get image. i hope this will help you;

Answer 3

Your current query:-
SELECT *
FROM images i
JOIN users u
ON u.user_id = i.user_id
LIMIT 1
uses LIMIT 1. This tells the query to bring back 1 row.
Removing the LIMIT 1 will return 1 or more records per user (who has at least 1 image), one for each image.
If you want a single user then it is possible (although not recommended) to (ab)use the GROUP BY clause:-
SELECT *
FROM images i
JOIN users u
ON u.user_id = i.user_id
GROUP BY u.user_id
This would bring back one record per user, but which image it returns is not defined. It could bring back the first image for that user, or the last one, or any other one (and which one it returns could change in the future). Further, there is no actual reason it couldn't return values from different rows for each of the columns on the images table (unlikely, but nothing specified to stop this happening).
Note that basic SQL standards specify (with a small exception) that any non aggregate field brought back in a SELECT statement must be in the GROUP BY clause. MySQL used to not enforce this restriction by default, but recently this changed and it is enforced by default. As such by default this query would no longer work as it is returning all the fields from the images and users tables while only specifying the user_id from the users table in the GROUP BY clause.
What you should do is define which image you want for each user. Assuming the first image (and that the images table uses an auto increment primary key called id):-
SELECT u.*,
i.*
FROM users u
LEFT OUTER JOIN
(
SELECT user_id
MIN(id) AS first_image_id
FROM images
GROUP BY user_id
) sub0
ON u.user_id = sub0.user_id
LEFT OUTER JOIN images i
ON sub0.user_id = i.user_id AND sub0.first_image_id = i.id
This uses a sub query to get the first image id for each user. Then that is joined to the images table to get the other details for that image from the images table.
Note I have used LEFT OUTER JOIN. This is to return a row for a user who doesn't have any images uploaded.
Note it is generally a bad idea to use SELECT *, rather than specifying the columns to be returned. I have left this in place here as I do not know the column names of your tables.