MySQL foreign key query returning empty - mysql

Question

I have three tables
Let's a demo_organization ;
+--------------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| org_name | varchar(100) | NO | | NULL | |
| org_type | varchar(100) | NO | | NULL | |
| abn_acn_no | varchar(100) | NO | | NULL | |
| org_url | varchar(120) | NO | | NULL | |
| notes | longtext | NO | | NULL | |
| city | varchar(100) | YES | | NULL | |
Second one is demo_user
mysql> desc demo_user ;
+--------------------+----------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------------+----------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| user_name | varchar(100) | NO | | NULL | |
| first_name | varchar(100) | NO | | NULL | |
| middle_name | varchar(100) | NO | | NULL | |
| last_name | varchar(100) | NO | | NULL | |
| image | varchar(10000) | YES | | NULL | |
| password | varchar(80) | NO | | NULL | |
| role | varchar(20) | NO | | NULL | |
| org_name_id | int(11) | NO | MUL | NULL | |
| timezone_id | int(11) | NO | MUL | NULL | |
And third one is the demo_meeting;look like
mysql> desc demo_meeting ;
+--------------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(200) | NO | | NULL | |
| meetingID | varchar(50) | NO | | NULL | |
| venue_id | int(11) | YES | MUL | NULL | |
| status | int(11) | YES | | NULL | |
| recurring_time | varchar(50) | NO | | NULL | |
| attendee_passwd | varchar(100) | NO | | NULL | |
| moderator_passwd | varchar(100) | NO | | NULL | |
| date_created | datetime | NO | | NULL | |
| start_time | varchar(100) | NO | | NULL | |
| end_time | varchar(100) | NO | | NULL | |
| meeting_duration | varchar(100) | NO | | NULL | |
| meeting_datetime | datetime | YES | | NULL | |
| timezone | varchar(50) | NO | | NULL | |
| reminder | tinyint(1) | NO | | NULL | |
| duration | varchar(20) | NO | | NULL | |
| created_by_id | int(11) | NO | MUL | NULL | |
In third table created_by_id refers to A user of demo_user table(Foreign key)
And org_name_id(demo_user table ) refers to the demo_organization (Foreign key to demo_organization table )
Updated
mysql> desc demo_meetingroom;
+------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(100) | NO | | NULL | |
| type | varchar(200) | NO | | NULL | |
| expired_on | varchar(100) | NO | | NULL | |
| user_id | int(11) | YES | MUL | NULL | |
+------------+--------------+------+-----+---------+----------------+
Now i am trying to get all meetings for a particular organization .
I am writing a query like
select meetingID ,type from demo_meeting as dm ,demo_meetingroom as dmr
Where venue_id IS NOT NULL
and dm.name = dmr.name
AND created_by_id IN
(
SELECT id from demo_user WHERE org_name_id IN
(
SELECT id from demo_organization where id =
(SELECT org_name_id from demo_user WHERE user_name = 'God')
)
);
Unfortunately it is returning me Empty set (But there is value )
Please help me out what might i am doing wrong ?

Answer 1

JOIN the three tables instead of these IN's. Something like:
SELECT
dm.meetingID,
dm.type
FROM demo_meeting dm
INNER JOIN demo_user u ON dm.created_by_id = u.id
INNER JOIN demo_organization org ON u.org_name_id = org.id
WHERE u.user_name = 'God'
AND dm.venue_id IS NOT NULL

Answer 2

Much better if you can use JOIN.
SELECT a.meetingID, d.type
FROM demo_meeting a
LEFT JOIN demo_user b
ON a.created_by_id = b.id
LEFT JOIN demo_organization c
ON b.org_name_id = c.id
LEFT JOIN demo_meetingroom d
ON a.name = d.name
WHERE a.venue_id IS NOT NULL AND
b.username = 'GOD'