Iterate list values from table - php

Question

I have two tables, who are joined and the ID of each table and element underneath are similar.
parentID | objectName | subID ID| className| subName |
_____________________________ ________________________
84 | Test | 14 14| BOM | Test
84 | More | 16 14| PDF | Test
84 | Sub | 15 15| Schematics | Test2
I want to list the categoryname and the subID of the related elements. Several ObjectNames will have several related classes.
PHP code:
$objects = mysqli_query($con,"SELECT * from subobject");
$join = mysqli_query($con, "SELECT * FROM subrelation AS subrelation INNER JOIN subobject AS subobject ON subobject.subId = subrelation.ID;");
echo "<ul>";
while($obj = mysqli_fetch_array($objects) and $row = mysqli_fetch_array($join))
{
echo "<li>". $obj['objectName'];
echo "<ul>";
//ITERATION GOES HERE
if($obj['objectName'] == $row['subName'])
echo "<li>". "$row[className]" . "</li>";
//END OF ITTERATION
echo "</ul>";
echo "</li>";
}
echo "</ul>";
?>
and output list:
-Test
-BOM
-Sub
-Schematics
-More
under each field there are supposed to be more listed values.

Answer 1

It looks like you need to simplify your code a bit. My guess is that your problem is occurring because you have different amounts of rows in each result set. This makes your while loop exit when it finishes going through the smaller result set (probably $objects), even though there's still more elements in the larger set.
A solution is to sort the results of your query, use just one condition in your while loop, and keep track of which objectName you're currently on using a string $curr_objectName:
$join = mysqli_query($con, 'SELECT * FROM subrelation AS subrelation INNER JOIN subobject AS subobject ON subobject.subId = subrelation.ID ORDER BY subobject.objectName;');
$curr_objectName = '';
echo '<ul>';
while($row = mysqli_fetch_array($join)) {
$subName = $row['subName'];
if($subName != $curr_objectName)) {
if($curr_objectName != '') {
#close the previous list
#will be skipped on the first loop iteration
echo '</ul>';
echo '</li>';
}
#start a new list
$curr_objectName = $subName;
echo '<li>'. $obj['objectName'];
echo '<ul>';
} else {
echo '<li>'. $row['className'] . '</li>';
}
}
echo '</ul>';