Question

I’m trying to build a query that will order results by date and time, but the date and time upon which I want to base the ordering is contained in two tables. Additionally, I’d like to group the data by loc_id for rows having the same date.

For example, if I had this data:

Notes:
– parent_id links to the id in TABLE A.
– there are two other tables USER and LOC which are used to get the user name and location name.
– comments are optional in TABLE A, but will always exist in TABLE B.

I’ve found a lot of info on this site that’s close to what I need, but nothing that’s quite helped me solve this issue.

Thanks.

Answer 1

SELECT a.`date`
     , a.`time`
     , l.loc_name AS l_name
     , a.rating
     , a.comment
     , u.user_name
FROM table_a AS a
  LEFT JOIN loc AS l 
    ON l.loc_id = a.loc_id
  LEFT JOIN `user` AS u
    ON u.user_id = a.user_id

UNION ALL

SELECT b.`date`
     , b.`time`
     , l.loc_name AS l_name
     , NULL AS rating
     , b.comment
     , u.user_name
FROM table_b AS b
  LEFT JOIN table_a AS a
    ON a.id = b.parent_id
  LEFT JOIN loc AS l 
    ON l.loc_id = a.loc_id
  LEFT JOIN `user` AS u
    ON u.user_id = b.user_id

ORDER BY `date`
       , l_name
       , `time`