how to combine and sort two different tables together in Mysql

问题

I have table A:

id username firstname event_date
1   Ben      lori     2014-01-27
2   Ben      lori     2014-01-04
3   Mary     john     2014-01-28

I have table B:

   id username event_date
   1   Ben     2014-01-23
   2   Nicole  2014-01-26

I want the result to be like this: Is there any solution that allow me to combine and sort it according to event_date like one table,like this:

  2   Ben      lori     2014-01-04     
            1   Ben     2014-01-23
            2   Nicole  2014-01-26
  1   Ben      lori     2014-01-27
  3   Mary     john     2014-01-28

so that I can use something like while loop or mysql_fetch_assoc to display the content

回答1:

Basically, you need union all:

select id, username, firstname, event_date
from ((select id, username, firstname, event_date
       from tablea
      ) union all
      (select id, username, NULL as firstname, event_date
       from tablea
      )
     ) t
order by event_date;

回答2:

Maybe you are looking for something like this:

SELECT * FROM tableA FULL OUTER JOIN tableB ORDER BY event_date

来源：https://stackoverflow.com/questions/21493530/how-to-combine-and-sort-two-different-tables-together-in-mysql