Combine rows from two tables with different columns? - mysql

Question

I'm having a hard time wrapping my head around this one. I believe it's happening because I am joining the two separate tables based on the same column (user_id), but I don't know how to fix it because the only thing in common between the two tables IS the user_id column.
Here is the query.
SELECT users_data_existing.`date`,`message`,`action`,`status`,`data`,
users_data_new.`date`,`data_new`
FROM users_data_existing
INNER JOIN users_data_action USING (action_id)
INNER JOIN users_data_status_user USING (status_user_id)
INNER JOIN `users` USING (user_id)
INNER JOIN users_data_new USING (user_id)
INNER JOIN data ON users_data_existing.`data_id` = data.`id`
WHERE users_data_existing.`user_id` = 2
ORDER BY users_data_existing.`date`,users_data_new.`date` DESC
The result, is that the users_data_new.date and data_new columns, are concatenated or "appended" to the previous rows.
+----------+-----------+-----------+-----------+-----------+----------+-----------+
| date | message | action | status | data | date | data_new |
+----------+-----------+-----------+-----------+-----------+----------+-----------+
|2011-01-01| data | data | data | data |2011-01-02| data_new |
-----------------------------------------------------------------------------------
|2011-01-01| data | data | data | data |2011-01-03| data_new1 |
-----------------------------------------------------------------------------------
REPEATS PATTERN FOR TOTAL RECORDS IN users_data_new TABLE
+----------+-----------+-----------+-----------+-----------+----------+-----------+
| date | message | action | status | data | date | data_new |
+----------+-----------+-----------+-----------+-----------+----------+-----------+
|2011-01-01| data1 | data1 | data1 | data1 |2011-01-02| data_new |
-----------------------------------------------------------------------------------
|2011-01-01| data1 | data1 | data1 | data1 |2011-01-03| data_new1 |
-----------------------------------------------------------------------------------
But that's not what I need. How can I get the last two columns into a separate row? I think a UNION would resolve this but I can't do that because the tables are almost identical but don't share the message column.

Answer 1

As suspected in the question, it was a UNION that I needed. The trick was to create an empty column in users_data_new to match users_data_existing. I also had a challenge with sorting it so I will include that here as well.
(SELECT data_existing.date AS submitdate,status_user.status,action.action,
data.data,data_existing.message
FROM users_data_existing AS data_existing
INNER JOIN users_requested_status_user status_user
ON data_existing.status_user_id = status_user.status_user_id
INNER JOIN users_requested_action action
ON data_existing.action_id = action.action_id
INNER JOIN websites data
ON data_existing.data_id = data.id
ORDER BY data_existing.date DESC) //sorts sub-query
UNION ALL
(SELECT data_new.date AS submitdate,status_user.status,
action.action,data_new.data_new,'' message //needed to add this last empty column
FROM users_data_new AS data_new
INNER JOIN users_requested_status_user status_user
ON data_new.status_user_id = status_user.status_user_id
INNER JOIN users_requested_action action
ON data_new.action_id = action.action_id
ORDER BY data_new.date DESC) //sorts sub-query
ORDER BY submitdate DESC"; //sorts the entire result
Keep in mind that with the alias for the date, the associative array key will be whatever alias name you use. i.e. $result['submitdate']