Best way to output results from two unidentical database tables - php

Question

I have two tables in my database announcements and announcements_external:
+----------+ +----------+
| table1 | | table2 |
+----------+ +----------+
| id | | id |
| catid | | eid |
| uid | | username |
| title | | source |
| text | | title |
| views | | section |
| images | | category |
| created | | text |
| modified | | views |
| pubdate | | images |
+----------+ | created |
| modified |
+----------+
In CodeIgniter framework, I want to merge them, so when I will do a foreach($results as $item), I would output them side by side, ordered by field created.
I tried this code but I know it's completly wrong with the merging:
public function get_mixed( $limit = NULL, $offset = NULL )
{
$this->db
->select('
announcements.id,
announcements.catid,
announcements.uid,
section.title AS section,
categories.title AS category,
announcements.title,
announcements.text,
announcements.views,
announcements.created,
announcements.modified,
announcements.pubdate,
announcements_external.id as eid,
announcements_external.eid,
announcements_external.source,
announcements_external.username,
announcements_external.section as esection,
announcements_external.category as ecategory,
announcements_external.title as etitle,
')
->join('categories', 'announcements.catid = categories.id', 'left')
->join('categories as section', 'categories.pid = section.id', 'left')
->join('announcements_external', 'announcements_external.id = announcements_external.id', 'right')
->order_by('created DESC, '.$this->_order_by);
$query = $this->db->get( $this->_table_name, $limit, $offset )->result();
return $query;
}
By the way, I do LEFT JOIN on categories table, which works as it should, but I thought it would be better to leave it in this code so you will see it also.
Any solution or maybe guide where I can get more information pls ? Thanks

Answer 1

It seems that Table1 and Table2 are separated entities so you need to use UNION ALL instead of JOIN to merge them.
(SELECT ..needed columns .. , Table1.created FROM Table1 JOIN categories ... )
UNION All
(SELECT ..needed columns .. , Table2.created FROM Table2 JOIN categories ... )
ORDER BY created ;
You will need to use fake columns aliases for nonidentical columns, if necessary.