mysql - Why is my union of two queries not ordering correctly? - 


 (select `size`, `type` `table` `type`='a' order `size` asc) union  (select `size`,`type` `table` `type`='b' order `size` desc)

why isn't query working hope? separates result array types 'a' , types 'b', within type 'a' results, not ordered size (size positive bigint).

any suggestions? :)

the results of query not ordered, unless use order by clause (or in mysql group by clause). try want:

(select `size`, `type` `table` `type`='a') union  (select `size`,`type` `table` `type`='b') order type,          (case when `type` = 'a' size end) asc,          (case when `type` = 'b' size end) desc;

ordering clauses on subqueries ignored (the exception when have limit). and, when not ignored may have not effect on outer query.

actually, forget union all entirely:

select size, `type` table type in ('a', 'b') order type,          (case when `type` = 'a' size end) asc,          (case when `type` = 'b' size end) desc;

the first type in order by clause unnecessary, think makes intention of ordering clearer.


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