Question

i have three tables i would like to link in this one query.

The script is an attendance register, so it records an attendance mark for each meeting, per user.

The three tables used:

“team”:

id | fullname | position         | class | hidden
1  | Team     | --               | black | 1
2  | Dan S    | Team Manager     | green | 0
3  | Harry P  | Graphic Engineer | blue  | 0

“register”:

id | mid | uid | mark
1  | 1   | 2   | /
2  | 1   | 3   | I
3  | 2   | 1   | /
4  | 2   | 3   | /

“meetings”:

id | maintask            | starttime  | endtime
1  | Organise Year Ahead | 1330007400 | 1330012800
2  | Gather Ideas        | 1330612200 | 1330617600
3  | TODO                | 1331217000 | 1331222400

There is a sample of the data. What i want to do is:

Select all the results from the register, group them by the user, and order them by the meeting start time. But, if there is not a mark in the register table, i want it to display “-” (can be done via php if needed) So an expected result like so:

fullname | mark | mid
Dan S    | /    | 1
Dan S    | /    | 2
Dan S    | -    | 3
Harry P  | I    | 1
Harry P  | /    | 2
Harry P  | -    | 3

My SQL Query is this at the moment:

SELECT u.fullname,u.id,r.mark,r.mid FROM team u FULL JOIN register r ON r.uid=u.id LEFT JOIN meetings m ON
r.mid=m.id GROUP BY u.id ORDER BY m.starttime ASC

And i get an error back from MySQL:

You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to use
near ‘FULL JOIN register r ON r.uid=u.id LEFT JOIN meetings m
ON r.mid=m.`id’ at line 1

But, i cant see an issue with it :S

Please could someone help out, point me in the right direction or give me a possible solution to this. Much Appreciated

Dan

Answer:
Query that worked:

   SELECT     
       u.fullname,    u.id as uid,    
       if(r.uid = u.id, r.mark, '-') as mark,    
       if(r.uid = u.id, r.mid, '-') as mid,    
       r.mid,    m.starttime 
   FROM     
       team u 
         CROSS JOIN     
       register r ON u.id = r.uid
         LEFT OUTER JOIN     
       meetings m ON r.mid = m.id  
   WHERE    
       u.hidden = 0 
   GROUP BY     
       u.id, r.mid 
   ORDER BY     
       m.starttime, u.id ASC

Answer 1

Full outer join is not supported by MySQL. At least to version 5.6, you can check MySQL Join doc. A cross join may be a workaround:

EDITED

SELECT 
   UxM.fullname,
   r.mark,
   UxM.mid,
   UxM.starttime
FROM 
   ( select u.id as uid, m.id as mid, u.fullname, m.starttime
     from
     team  u
      CROSS JOIN   
     meetings ) UxM
   left join
   register r
      on UxM.uid = r.uid and UxM.mid = r.mid
ORDER BY 
   UxM.starttime ASC

Let me know if this solve your issue.

---

A simplification:

SELECT     
    u.fullname,
    u.id AS uid,    
    COALESCE(r.mark, '-') AS mark,    
    COALESCE(r.mid, '-') AS mid,    
    m.id,
    m.starttime 
FROM     
    team u 
      CROSS JOIN     
    meetings m 
      LEFT JOIN     
    register r
        ON   r.mid = m.id  
        AND  r.id = u.uid
WHERE    
    u.hidden = 0 
GROUP BY     
    m.id, u.id 
ORDER BY     
    m.starttime, u.id