sql - Select distinct tuples in mysql -


i'm having hard time reasoning problem:

given table:

 +------+------------+ | id   | sibling_id | +------+------------+ |    1 |       null | |    2 |          3 | |    3 |          2 | |    4 |          5 | |    5 |          4 | +------+------------+

if choose ids (1,2,3,5), i'd (1,2,4), because 3 points 2, , 2 points 3, want 1 of both.

expected output:

 +------+------------+ | id   | sibling_id | +------+------------+ |    1 |       null | |    2 |          3 | |    4 |          5 | +------+------------+

how mysql (5.7) ?

solution :

select distinct least(id, coalesce(sibling, id)) test id in (1,2,3,5);

thanks !

you have make sure, tuples same (meaning example being (2,3) , not (3,2)). can putting smaller value in front , greater value @ end of tuple. use least() , greatest() it.

select  distinct least(id, sibling_id), greatest(id, sibling_id) table id in (1,2,3,5);

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