MySQL - How get this result? - mysql

Question

I have a two tables.
work:
+----+----------+
| id | position |
+----+----------+
| 1 | 1 |
| 2 | 2 |
+----+----------+
content:
+----+---------+------+-------------+
| id | work_id | name | translation |
+----+---------+------+-------------+
| 1 | 1 | Kot | 1 |
| 2 | 1 | Cat | 2 |
| 3 | 2 | Ptak | 1 |
| 4 | 2 | Bird | 2 |
| 5 | 2 | Ssss | 3 |
+----+---------+------+-------------+
I want to get result like this:
+----+------+----------+
| id | name | sortName |
+----+------+----------+
| 1 | Kot | NULL |
| 1 | Cat | NULL |
| 2 | Ptak | Ssss |
| 2 | Bird | Ssss |
+----+------+----------+
My not working query is here:
select
w.id,
c.name,
cSort.name as sortName
from
work w
LEFT JOIN
content c
ON
(w.id=c.work_id)
LEFT JOIN
content cSort
ON
(w.id=cSort.work_id)
WHERE
c.translation IN(1,2) AND
cSort.translation=3
ORDER BY
sortName
I want to get for each work at least one translation and secound if exist (translation=1 always exist). And for every row I want special column with translation used to sort. But Not always this translation exist for work.id. In this example I want to sort work by translation=3.
Sorry for my not fluent english. Any ideas?
Best regards

Answer 1

/*
create table work ( id int, position int);
insert into work values
( 1 , 1 ),
( 2 , 2 );
create table content(id int, work_id int, name varchar(4), translation int);
insert into content values
( 1 , 1 , 'Kot' , 1),
( 2 , 1 , 'Cat' , 2),
( 3 , 2 , 'Ptak' , 1),
( 4 , 2 , 'Bird' , 2),
( 5 , 2 , 'Ssss' , 3);
*/
select w.id,c.name,(select c.name from content c where c.work_id = w.id and c.translation = 3) sortname
from work w
join content c on w.id = c.work_id
where c.translation <> 3;
result
+------+------+----------+
| id | name | sortname |
+------+------+----------+
| 1 | Kot | NULL |
| 1 | Cat | NULL |
| 2 | Ptak | Ssss |
| 2 | Bird | Ssss |
+------+------+----------+

Answer 2

So translation is also a work_id and you consider translation = 3 a translation in your example and translation <> 3 an original. You want to join each original record with every translation record where the latter's work_id matches the former's translation.
I think you are simply confusing IDs here. It should be ON (w.translation = cSort.work_id).
Another way to write the query:
select o.work_id as id, o.name, t.name as sortname
from (select * from content where translation <> 3) o
left join (select * from content where translation = 3) t
on t.work_id = o.translation
order by t.name;
There seems to be no need to join table work.
I'd like to add that the table design is a bit confusing. Somehow it is not clear from it what is a translation for what. In your example you interpret translation 3 as a translation for the non-three records, but this is just an example as you say. I don't find this readable.
UPDATE: In order to sort your results by work.position, you can join that table or use a subquery instead. Here is the order by clause for the latter:
order by (select position from work w where w.id = o.work_id);