Question

Is there a way in SQL (MySQL) to do a ’round robin’ ORDER BY on a particular field?

As an example, I would like to take a table such as this one:

+-------+------+ | group | name | +-------+------+ |     1 | A    | |     1 | B    | |     1 | C    | |     2 | D    | |     2 | E    | |     2 | F    | |     3 | G    | |     3 | H    | |     3 | I    | +-------+------+ 

And run a query that produces results in this order:

+-------+------+ | group | name | +-------+------+ |     1 | A    | |     2 | D    | |     3 | G    | |     1 | B    | |     2 | E    | |     3 | H    | |     1 | C    | |     2 | F    | |     3 | I    | +-------+------+ 

Note that the table may have many rows, so I can’t do the ordering in the application. (I’d obviously have a LIMIT clause as well in the query).

Answer 1

What you can do is create a temporary column in which you create sets to give you something like this:

+-------+------+-----+ | group | name | tmp | +-------+------+-----+ |     1 | A    |   1 | |     1 | B    |   2 | |     1 | C    |   3 | |     2 | D    |   1 | |     2 | E    |   2 | |     2 | F    |   3 | |     3 | G    |   1 | |     3 | H    |   2 | |     3 | I    |   3 | +-------+------+-----+ 

To learn how to create the sets, have a look at this question/answer.

Then its a simple

ORDER BY tmp, group, name