Selecting entire rows from two tables - mysql

Question

I don't know if it's possible and i might be asking a stupid question here, if so, forgive me.
I have two tables that are somewhat similar but not entirely.
Table 1 (user_opinions)
| o_id | user_id | opinion |is_shared_from| date,isglobal etc
|:---------|---------|:------------:|:------------:|
| 1 | 11| text 1 | 0
| 2 | 13| text 2 | 2
| 3 | 9| text 3 | 0
Table 2 (Buss_opinions)
| bo_id | o_id | user_id | opinion | date
|:---------|--------|:------------:|:------------:|
| 1 | 2| 52 | bus text 1
| 2 | 3| 41 | bus text 2
If i do a standard select and join like this:
SELECT * FROM user_opinions uo
JOIN Buss_opinions bo
ON uo.o_id = bo.o_id
This will return rows with both table's data joined together.
My question is, what if i wanted to get data from these two tables in seperate rows.
Result should be something like this:
| oid | bo_id | opinion | nb: and other rows from both tables
|:---------|---------|:------------:|
| 1 | NULL | text 1 | nb:from table 1
| NULL | 1| bus text 1| nb:from table 2
| 2 | NULL | text 2 |nb:from table 1
and so on
It gets both table's data and where there's no common field it puts a NULL value in the field. Is there a type of join for this? or are there other ways of doing this?

Answer 1

One way you could go about it is using a UNION (http://dev.mysql.com/doc/refman/5.0/en/union.html):
SELECT oid AS OID, null AS BOID, user_id AS USERID, opinion AS Opinion
FROM table1
UNION
SELECT null AS OID, bo_id AS BOID, user_id AS USERID, opinion AS Opinion
FROM table2
Edit: You could even take this a step further and marry it with the CONCAT function:
SELECT CONCAT('OID-', oid) AS ID, user_id AS USERID, opinion AS Opinion
FROM table1
UNION
SELECT CONCAT('BOID-', bo_id) AS ID, user_id AS USERID, opinion AS Opinion
FROM table2