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MySQL - Select Max Unique Order By
Posted on 2007-12-06
I am trying to create a list of data where id is sorted highest to lowest, but where each name is unique.
For example:
name : id : text
aaaa : 11 : stuff
bbbb : 12 : more stuff
aaaa : 13 : other stuff
bbbb : 14 : more other stuff
Query should return only one name for it's highest id only so:
bbbb : 14 : more other stuff
aaaa : 13 : other stuff
Thanks for reading.
For example:
name : id : text
aaaa : 11 : stuff
bbbb : 12 : more stuff
aaaa : 13 : other stuff
bbbb : 14 : more other stuff
Query should return only one name for it's highest id only so:
bbbb : 14 : more other stuff
aaaa : 13 : other stuff
Thanks for reading.
SELECT name, MAX(id) AS id, text,
option
FROM dataset1
LEFT OUTER JOIN dataset2 ON name_fk = name
WHERE something!=1
GROUP BY name
ORDER BY id DESC
LIMIT 15;
[X]
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6 Comments
SELECT name, id, text,
option
FROM dataset1
LEFT OUTER JOIN dataset2 ON name_fk = name
WHERE something!=1
AND id = (SELECT MAX(ID) from dataset1 x where x.name = dataset1.name)
GROUP BY name
ORDER BY id DESC
LIMIT 15;
option
FROM dataset1
LEFT OUTER JOIN dataset2 ON name_fk = name
WHERE something!=1
AND id = (SELECT MAX(ID) from dataset1 x where x.name = dataset1.name)
GROUP BY name
ORDER BY id DESC
LIMIT 15;
Thanks, what about:
For example:
name : id : text : other :
aaaa : 11 : stuff : 5 :
bbbb : 12 : more stuff : 10 :
aaaa : 13 : other stuff : 12 :
bbbb : 14 : more other stuff : 1 :
Query should return only one name for it's highest other only so:
aaaa : 13 : other stuff : 12 :
bbbb : 12 : more stuff : 10 :
the field other is part of table dataset1
For example:
name : id : text : other :
aaaa : 11 : stuff : 5 :
bbbb : 12 : more stuff : 10 :
aaaa : 13 : other stuff : 12 :
bbbb : 14 : more other stuff : 1 :
Query should return only one name for it's highest other only so:
aaaa : 13 : other stuff : 12 :
bbbb : 12 : more stuff : 10 :
the field other is part of table dataset1
SELECT * FROM
(
SELECT name, id, text, other
FROM dataset1
LEFT OUTER JOIN dataset2 ON name_fk = name
WHERE something!=1
GROUP BY name
ORDER BY other desc
) AS Y
ORDER BY id DESC
LIMIT 15;
(
SELECT name, id, text, other
FROM dataset1
LEFT OUTER JOIN dataset2 ON name_fk = name
WHERE something!=1
GROUP BY name
ORDER BY other desc
) AS Y
ORDER BY id DESC
LIMIT 15;
i hope you always need only the highest id , what ever your field names are.
Most simple way seems like this.
Check this out...
select id, ename, text from Data a
where id in (select max(id) from Data group by ename)
order by id
Most simple way seems like this.
Check this out...
select id, ename, text from Data a
where id in (select max(id) from Data group by ename)
order by id
The problem with that imitchie is that it sorts the whole table, is there anyway to avoid sorting the whole table before selecting just the 15 records?
The problem is that the way you have prescribed the problem domain requires that you do sort everything, group them in a Particular order, then Sort them by a secondary order, however the limit 15 is applied to the Secondary order! You might just want to revisit what you can live with. Because there is an inherent dependancy in there.
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