Joining tables in SQL

Question

I am having trouble with a SQL query.

SELECT t.topicname, m. *, ms.avatar
   FROM `messages` m
    INNER JOIN topics t ON m.topicid = t.topicid
    inner join users u on m.author=u.username
    inner join misc ms on u.userid=ms.userid
   ORDER BY postdate DESC LIMIT 5

what i want to do is get the topicname from the topics table, everything from the messages table and avatar from the misc table

I join the topics and messages table by the topicid I can join the messgages and users table by messages.author and users.username and to join to the misc table i join on users.userid and misc.userid

The problem is I am not getting the results I want

This query works on the messages and topics tables joined but i need to add the misc table and the only way to join that is throught the users table

SELECT t.topicname, m. *
   FROM `messages` m
    INNER JOIN topics t ON m.topicid = t.topicid
    ORDER BY postdate DESC LIMIT 5

Here is the table structure

CREATE TABLE `messages` (
  `messageid` int(6) NOT NULL auto_increment,
  `boardid` int(2) NOT NULL default '0',
  `topicid` int(4) NOT NULL default '0',
  `message` text NOT NULL,
  `author` varchar(255) NOT NULL default '',
  `postdate` datetime default NULL,
  PRIMARY KEY  (`messageid`)
)

CREATE TABLE `misc` (
  `miscid` int(4) NOT NULL auto_increment,
  `userid` int(4) NOT NULL default '0',
  `profpic` varchar(100) NOT NULL default '',
  `avatar` varchar(100) NOT NULL default '',
  `signature` text NOT NULL,
  `alerts` enum('y','n') NOT NULL default 'y',
  PRIMARY KEY  (`miscid`)
)

CREATE TABLE `topics` (
  `topicid` int(4) NOT NULL auto_increment,
  `boardid` int(2) NOT NULL default '0',
  `topicname` varchar(255) NOT NULL default '',
  `author` varchar(255) NOT NULL default '',
  `counter` int(5) NOT NULL default '0',
  `sticky` char(1) NOT NULL default 'n',
  `locked` char(1) NOT NULL default 'n',
  PRIMARY KEY  (`topicid`)
)

CREATE TABLE `users` (
  `userid` int(25) NOT NULL auto_increment,
  `first_name` varchar(25) NOT NULL default '',
  `last_name` varchar(25) NOT NULL default '',
  `email` varchar(255) NOT NULL default '',
  `username` varchar(25) NOT NULL default '',
  PRIMARY KEY  (`userid`)
)

This is the output of the query with only 2 joins and this is what i expect to get (only i want to have an avatar with it)

It doesn't llok to pretty here but that is what the database gives me

topicname         messageid       boardid         topicid         message         author      postdate
Mauris Eu Neque Ipsum   36  4   8   Suspendisse nibh risus, porta at cursus sed, tinci...   iTuneStinker    2010-04-08 20:31:39
Aliquam Erat Volutpat   35  5   15  Donec volutpat ligula eu lorem pharetra a adipisci...   AwsomeMoon  2010-04-07 21:58:20
Ut Non Risus Elit   34  2   14  Etiam cursus, erat sed placerat fringilla, risus a...   ScaryHair   2010-04-07 15:35:34
Quisque Rutrum Mattis Sagittis  33  5   9   Etiam in elit sit amet nulla scelerisque ultricies...   ScaryHair   2010-04-07 15:33:46
Where Do I Start Trying To Organise A Festival  32  3   12  Morbi a neque aliquam nisl varius lobortis. Sed ve...   ScaryHair   2010-04-07 13:27:40

and here is the result using the query that joins all tables

topicname         messageid       boardid         topicid         message         author      postdate        avatar
Forum Rules And Guidelines  2   1   1   FORUM RULES     AdRock  2009-04-11 23:05:18     avatar_17200.jpg
Forum Rules And Guidelines  3   2   2   FORUM RULES.    AdRock  2009-04-11 23:05:18     avatar_17200.jpg
Forum Rules And Guidelines  4   3   3   FORUM RULES     AdRock  2009-04-11 23:05:18     avatar_17200.jpg
Forum Rules And Guidelines  5   4   4   FORUM RULES     AdRock  2009-04-11 23:05:18     avatar_17200.jpg
Forum Rules And Guidelines  6   5   5   FORUM RULES     AdRock  2009-04-11 23:05:18     avatar_17200.jpg

The first quert gets the last 5 records of the messages table and that is what i want but i want to be able to get the avatar that relates to the author of each message

Answer 1

Seems you don't have users and avatars filled for each message.

Try replacing the INNER JOINS with the OUTER JOINS.

SELECT  t.topicname, m. *, ms.avatar
FROM    `messages` m
JOIN    topics t
ON      t.topicid = m.topicid
LEFT JOIN
        users u
ON      u.username = m.author
LEFT JOIN
        misc ms
ON      ms.userid = u.userid
ORDER BY
        m.postdate DESC
LIMIT 5