Multiple select statements on different tables with different constraints in single query, show no results as nulls

I use several queries on multiple tables that I'd like to combine into a single query for efficiency and speed.

My tables look like this:

m1
------------------------------------------------------------------------
id  |   time    |   min |   max     |   mean
------------------------------------------------------------------------
a       00:10:00    1       5       3
a       00:20:00    2       6       4
a       00:30:00    3       7       5
a       00:开发者_Go百科40:00    4       8       6
b       00:40:00    11      15      13
b       00:50:00    21      26      24
c       00:10:00    21      27      25

m2
------------------------------------------------------------------------
id  |   time    |   min |   max     |   mean
------------------------------------------------------------------------
a       00:30:00    22      44      33
a       00:40:00    33      55      44
a       00:50:00    44      66      55
b       00:20:00    1       4       2
b       00:30:00    1       3       2
b       00:30:00    2       5       4
c       00:20:00    6       7       6

m3
------------------------------------------------------------------------
id  |   time    |   min |   max     |   mean
------------------------------------------------------------------------
b       00:10:00    11      15      13
b       00:20:00    21      26      14
c       00:00:00    21      27      25

My queries look like this:

SELECT min,max,mean FROM m1 WHERE id='a' AND time='00:10:00'
SELECT min,max,mean FROM m2 WHERE id='a' AND time='00:10:00'
SELECT min,max,mean FROM m3 WHERE id='a' AND time='00:10:00'
SELECT min,max,mean FROM m1 WHERE id='a' AND time='00:20:00'
SELECT min,max,mean FROM m2 WHERE id='a' AND time='00:20:00'
SELECT min,max,mean FROM m3 WHERE id='a' AND time='00:20:00'
SELECT min,max,mean FROM m1 WHERE id='a' AND time='00:30:00'
SELECT min,max,mean FROM m2 WHERE id='a' AND time='00:30:00'
SELECT min,max,mean FROM m3 WHERE id='a' AND time='00:30:00'
SELECT min,max,mean FROM m1 WHERE id='a' AND time='00:40:00'
SELECT min,max,mean FROM m2 WHERE id='a' AND time='00:40:00'
SELECT min,max,mean FROM m3 WHERE id='a' AND time='00:40:00'
SELECT min,max,mean FROM m1 WHERE id='a' AND time='00:50:00'
SELECT min,max,mean FROM m2 WHERE id='a' AND time='00:50:00'
SELECT min,max,mean FROM m3 WHERE id='a' AND time='00:50:00'

I take results of these queries and manually put them together into an array that looks like this:

----------------------------------------------------------------------------------------------------------------------------------------------------------------
#|  time    |   m1.min  |   m1.max  |   m1.mean |   m2.min  |   m2.max  |   m2.mean |   m3.min  |   m3.max  |   m3.mean 
----------------------------------------------------------------------------------------------------------------------------------------------------------------
1   00:10:00    1           5           3           NULL        NULL        NULL        NULL        NULL        NULL
2   00:20:00    2           6           4           NULL        NULL        NULL        NULL        NULL        NULL
3   00:30:00    3           7           5           22          44          33          NULL        NULL        NULL
4   00:40:00    NULL        NULL        NULL        33          55          44          NULL        NULL        NULL
5   00:50:00    NULL        NULL        NULL        44          66          55          NULL        NULL        NULL

I have been trying to figure out how to generate the above array with either one sql statement, or one sql statement per time stamp. I've tried joins, unions, case statements, etc. with no luck. The fact that I need to display a 'NULL' or have a blank value in the columns where there are no matching results is what seems to complicate things.

I am using PostgreSQL 8.3.6.

Any help would be greatly appreciated.

---

The closest solution I found is to use FULL OUTER JOIN like this:

SELECT
    time,
    COALESCE(m1.min::text, 'NULL')  AS "m1.min",
    COALESCE(m1.max::text, 'NULL')  AS "m1.max",
    COALESCE(m1.mean::text, 'NULL') AS "m1.mean",
    COALESCE(m2.min::text, 'NULL')  AS "m2.min",
    COALESCE(m2.max::text, 'NULL')  AS "m2.max",
    COALESCE(m2.mean::text, 'NULL') AS "m2.mean",
    COALESCE(m3.min::text, 'NULL')  AS "m3.min",
    COALESCE(m3.max::text, 'NULL')  AS "m3.max",
    COALESCE(m3.mean::text, 'NULL') AS "m3.mean"
FROM
    (SELECT time, min, max, mean FROM m1 WHERE id = 'a') m1
    FULL JOIN
    (SELECT time, min, max, mean FROM m2 WHERE id = 'a') m2
    USING (time)
    FULL JOIN 
    (SELECT time, min, max, mean FROM m3 WHERE id = 'a') m3
    USING (time)
ORDER BY time;

Result:

   time   | m1.min | m1.max | m1.mean | m2.min | m2.max | m2.mean | m3.min | m3.max | m3.mean 
----------+--------+--------+---------+--------+--------+---------+--------+--------+---------
 00:10:00 | 1      | 5      | 3       | NULL   | NULL   | NULL    | NULL   | NULL   | NULL
 00:20:00 | 2      | 6      | 4       | NULL   | NULL   | NULL    | NULL   | NULL   | NULL
 00:30:00 | 3      | 7      | 5       | 22     | 44     | 33      | NULL   | NULL   | NULL
 00:40:00 | 4      | 8      | 6       | 33     | 55     | 44      | NULL   | NULL   | NULL
 00:50:00 | NULL   | NULL   | NULL    | 44     | 66     | 55      | NULL   | NULL   | NULL
(5 rows)