how to not get duplicate data in php mysql - php

Question

I have a mysql query in which i am fetching details from two tables now i want data of users whose requests are pending and from other data centers i want the pin codes that they have so i made this query which is working fine but it is giving me duplicate data for name and center too. this is my query
$sql = "
SELECT u.username
, u.district
, u.requests
, c.username
, c.id
FROM users u
JOIN center c
ON u.username = c.username
where u.requests = 'pending'
";
$result = mysqli_query($con, $sql);
if (mysqli_num_rows($result)>0) {
while ($row = mysqli_fetch_assoc($result)) {
$name = $row['username'];
$district = $row['district'];
$center = $row['id'];?>
<tr><td><?php echo $row['username']?></td><td><?php echo $row['district']?></td><td><?php echo $row['id']?></td></tr>
<?php
}
}
?>
The following provides a text representation of current output for better understanding.
name center pin code
dhruv mumbai 5545454
dhruv mumbai 2618165165
I want the $center variable in commas and don't want it to repeat the name and district variable, so something like this:

Answer 1

In MySQL you can use GROUP_CONCAT to get a comma separated list of values. Change your query to
$sql = "
SELECT u.username
, u.district
, u.requests
, GROUP_CONCAT(c.id) AS id
FROM users u
JOIN center c
ON u.username = c.username
where u.requests = 'pending'
GROUP BY u.username
, u.district
, u.requests";
Note I have removed c.username from the SELECT list as it is the same value as u.username (because of the JOIN condition) and since it has the same column name it will overwrite u.username in the output data.