MySQL: how to sort some records in ASC and some in DESC order, based on another field's value

Question

I have a table of "tickets".
Table structure:

• unique ID (auto-increment)
• status (open/closed/exception)
• priority (numeric, larger number = higher priority)
• creation_date
• etc...

I need to retrieve the tickets in the following order:

• "open" tickets first, sorted by priority (highest first), then by creation_date (oldest first)
• "closed" tickets next, sorted by creation_date (newest first)

This could be done with a UNION of two queries, but this would add a lot of complexity.

Any suggestions for accomplishing this in a single query?

Answer 1

Don't use union all . Use multiple keys in the order by :

select t.*
from t
where status in ('open', 'closed')
order by (status = 'open') desc,
         (case when status = 'open' then priority end) desc,
         (case when status = 'open' then creation_date end) asc,
         (case when status = 'closed' then creation_date end) desc