Get values from different tables inside a while loop statement using php - php

Question

I'm having an issue of retrieving values from two different tables. Here's the code so far:
$result = mysqli_query($conn,"SELECT * FROM articles");
$num = mysqli_num_rows($result);
while ($row = mysqli_fetch_array($result)) {
$uid=$row['_uid'];
$result2 = mysqli_query($conn, "SELECT _username FROM users WHERE _id = '$uid' ";
$num2 = mysqli_num_rows($result2);
while ($row2 = mysqli_fetch_array($result2)) {
$username = $row2['_username'];
}
$divtext='<h3>'.$row['_posttype'].'</h3> <h2>'.$username.' </h2>';
}
I've been reading that I should preform this while inside a while with multiple query, also found on w3 that you could directly assign a value to a variable directly using:
"SELECT _username INTO $username FROM users WHERE _id = '$uid' LIMIT 1";
But this works in SQL inside myadmin, in a php I can't find how to cast it.
I have also replace the fetch_row for fetch_assoc and still nothing, im struggling for two days already with this.

Answer 1

you could select al the value using a single query
SELECT a._uid , a._posttype, u._username
FROM articles a
INNER JOIN users u on a._uid = u._id
..
$result = mysqli_query($conn,
"SELECT a._uid , a._posttype, u._username
FROM articles a
INNER JOIN users u on a._uid = u._id");
$num = mysqli_num_rows($result);
while ($row = mysqli_fetch_array($result)) {
$divtext='<h3>'.$row['_posttype'].'</h3> <h2>'.$username.' </h2>';
}
$echo $divtext;