Trying to merge two results of SQL queries - ToDoList App - php

Question

I am trying to merge two results of two queries in MYSQL using PHP, but I am puzzled how to do it! I am using PDO. I am programming for a hobby and am trying to make a to do list app just like a Trello board. However, I just can't figure out how to merge two results from different tables in a database.
The idea is as follows:
I have a table called 'task_lists' with the content:
'list_id => 1, list_name = 'listOne'
'list_id => 2, list_name = 'listTwo'
And a table called 'tasks':
task_id => 1, list_id => 1, task_name => 'taskOfListOne', duration => 5, is_done => 1
task_id => 2, list_id => 1, task_name => 'anotherTaskOfListOne', duration => 5, is_done => 1
task_id => 3, list_id => 2, task_name => 'taskOfListTwo', duration => 10, is_done => 0
And I am trying to create an array that is merged between the two results as something like:
(I know this is a rough picture of how the array is supposed to look like)
$result = [array]
[list_id] = 1, [list_name] = 'listOne' =>
[array][list_id] = 1, ['task_name] = taskOfListOne,[duration] = 5, ['is_done'] => 1
[array][list_id] = 1, ['task_name] = anotherTaskOfListOne,[duration] = 5, ['is_done'] => 1
[list_id] = 2, [list_name] = 'listTwo' =>
[array][list_id] = 2, ['task_name] = taskOfListTwo,[duration] = 5, ['is_done'] => 1
Is this even possible? I have tried a Union sql query and methods like nested foreach statements, but none of them worked for me. Am I missing something here?
PS: Sorry for my bad english.

Answer 1

Have you tried a left join?
SELECT TL.`list_id`, TL.`list_name`, T.`task_name`, T.`duration`
FROM task_lists AS TL
LEFT JOIN tasks as T ON TL.`list_id` = T.`list_id`
And then in PHP you build the array in the format you want.
Later edit:
Simple PHP example to parse SQL data as you asked (to remove duplicated info):
<?php
// $mysql_rows -> here is your query result, fetched as associative array
$filtered_array = array();
foreach ($mysql_rows as $row){
// Initiate record if is not already initiated
if (!isset($filtered_array[ $row['list_id'] ])){
$filtered_array[ $row['list_id'] ] = array(
'list_id' => $row['list_id'],
'list_name' => $row['list_name'],
'tasks' => array()
);
}
// Add tasks
$filtered_array[ $row['list_id'] ]['tasks'][] = array(
'task_name' => $row['task_name'],
'duration' => $row['duration'],
'is_done ' => $row['is_done ']
);
}
// Optional: if you want to remove list_id from $filtered_array key names, uncomment the next line
// $filtered_array = array_values($filtered_array);
?>