MySQL Query - Select all posts and count comments for each one - php

Question

It's 3:30 AM in my country so I need to sleep but I can't without this:
I'm trying to get all posts (using Zend_Db) and count comments for each one.
Schema
blog_posts:
+---------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------------+------------------+------+-----+---------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| title | varchar(255) | NO | | NULL | |
| content | text | NO | | NULL | |
| alias | varchar(100) | NO | | NULL | |
| user_id | int(11) | NO | | NULL | |
| created_date | datetime | NO | | NULL | |
| modified_date | datetime | YES | | NULL | |
| thumbnail | varchar(255) | YES | | NULL | |
+---------------+------------------+------+-----+---------+----------------+
And here's blog_comments:
+---------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------------+------------------+------+-----+---------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| user_id | int(11) | NO | | NULL | |
| post_id | int(11) | NO | | NULL | |
| comment | text | NO | | NULL | |
| created_date | datetime | NO | | NULL | |
| modified_date | datetime | YES | | NULL | |
+---------------+------------------+------+-----+---------+----------------+
Note: the blog_comments.post_id is linked with blog_posts.id.
I would like a resulting table like that:
+---------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------------+------------------+------+-----+---------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| title | varchar(255) | NO | | NULL | |
| content | text | NO | | NULL | |
| alias | varchar(100) | NO | | NULL | |
| user_id | int(11) | NO | | NULL | |
| created_date | datetime | NO | | NULL | |
| modified_date | datetime | YES | | NULL | |
| thumbnail | varchar(255) | YES | | NULL | |
+---------------+------------------+------+-----+---------+----------------+
| TEMPOROARY COLUMN IN OBJECT ($post->comment) |
+---------------+------------------+------+-----+---------+----------------+
| comments | | | | | |
+---------------+------------------+------+-----+---------+----------------+
Now, here's the query I have for now:
SELECT `p`.*, `c`.*
FROM `blog_posts` `p`
LEFT JOIN (
SELECT COUNT(*)
FROM `blog_comments` `c`
WHERE c.post_id = p.id
) ON `p`.`comments`;
But it give me an error:
Error Code: 1248. Every derived table must have its own alias
So if someone can help me, it would be very appreciated!
IMPORTANT NOTE
I'm using Zend_Db and Zend_Db_Select so I must be able to use the functions like joinLeft() or anything I need.
This is in my model for the select():
$select = $this->table->select();
if ($alias) {
$select->where('alias = ?', $alias);
return $this->table->fetchRow($select);
}
if ($withComments) {
// I WILL PLACE THE CODE HERE, EXEMPLE:
$select->joinLeft(...);
}

Answer 1

SELECT p.*, x.*
FROM blog_posts p
LEFT JOIN
(
SELECT post_id, COUNT(*) as cc
FROM blog_comments
GROUP BY post_id
) x
ON x.post_id = p.id;