How to make this query run faster? - mysql

Question

I have query like this:
SELECT
`om_chapter`.`manganame` as `link`,
(SELECT `manganame` FROM `om_manga` WHERE `Active` = '1' AND `om_manga`.`link` = `om_chapter`.`manganame` LIMIT 0,1) AS `manganame`,
(SELECT `cover` FROM `om_manga` WHERE `Active` = '1' AND `om_manga`.`link` = `om_chapter`.`manganame` LIMIT 0,1) AS `cover`,
(SELECT `othername` FROM `om_manga` WHERE `Active` = '1' AND `om_manga`.`link` = `om_chapter`.`manganame` LIMIT 0,1) AS `othername`
FROM `om_chapter`
WHERE
`Active` = '1' AND
(SELECT `Active` From `om_manga` WHERE `om_manga`.`link` = `om_chapter`.`manganame` LIMIT 0,1) AND
`id` IN ( SELECT MAX(`id`) FROM `om_chapter` WHERE `Active` = '1' GROUP BY `manganame` )
ORDER BY `id` DESC LIMIT 10
So how can I make this query faster?
Here are my tables:
om_chapter:
id | manganame | chapter | Active
-----------------------------------------
1 | naruto | 1 | 1
2 | naruto | 12 | 1
3 | naruto | 22 | 1
4 | bleach | 10 | 1
5 | bleach | 15 | 1
6 | gents | 1 | 1
7 | naruto | 21 | 1
om_manga:
id | othername | manganame | cover | Active
-----------------------------------------------------
1 | naruto | naruto | n.jpg | 1
2 | bleach | bleach | b.jpg | 1
4 | gents | gents | g.jpg | 1
First thing i want form this query is to give me 10 last rows form om_chapter by grouping manganame and ordering by id.. i try to use a simple query by using group or even distinct but none of them give me the right result...
In a simple query with group or distinct, the result is like this:
id | manganame | chapter | Active
-----------------------------------------
7 | prince | 21 | 1
5 | gent | 15 | 1
2 | naruto | 12 | 1
1 | bleach | 1 | 1
But i want this result:
id | manganame | chapter | Active
-----------------------------------------
9 | gents | 21 | 1
8 | bleach | 21 | 1
7 | prince | 21 | 1
6 | naruto | 1 | 1
So i use this:
WHERE
`Active` = '1' AND
(SELECT `Active` From `om_manga` WHERE `om_manga`.`link` = `om_chapter`.`manganame` LIMIT 0,1) AND
`id` IN ( SELECT MAX(`id`) FROM `om_chapter` WHERE `Active` = '1' GROUP BY `manganame` )
And i use sub select in where because i want Active's field in om_manga's table be 1..
For the reset of sub select, i actually didn`t try join, but i will..!

Answer 1

I might have misunderstood your intentions.. But here's one try:
SELECT c.`manganame` AS `link`
, m.`manganame`
, m.`cover`
, m.`othername`
FROM
`om_manga` m
INNER JOIN `om_chapter` c
ON m.`link` = c.`manganame`
INNER JOIN
( SELECT `manganame`, MAX(`id`) AS `maxid`
FROM `om_chapter`
WHERE `Active` = '1'
GROUP BY `manganame` ) mx
ON mx.`maxid` = c.`id`
ORDER BY c.`id` DESC LIMIT 10

Answer 2

I would introduce a foreign key contstrain to the om_chapter table to account for the link from a manga to its corresponding chapters.
This is how I would conceptualize the problem.
A manga can have many chapters. A chapter belongs to one manga.
Then I would alter the om_chapter table, to include a foreign key for the chapter to link to the manga.
ALTER TABLE om_Chapter (
ADD mangaID int references om_Manga (id)
)
And drop the manganame column as it is just redundant now
ALTER TABLE om_Chapter (
DROP COLUMN manganame
)
Your tables then could look like this.
om_manga:
id | othername | manganame | cover | Active
-----------------------------------------------------
1 | naruto | naruto | n.jpg | 1
2 | bleach | bleach | b.jpg | 1
4 | gents | gents | g.jpg | 1
om_chapter:
id | chapter | Active | mangaID
-----------------------------------------
1 | 1 | 1 | 1
2 | 12 | 1 | 1
3 | 22 | 1 | 1
4 | 10 | 1 | 2
5 | 15 | 1 | 2
6 | 1 | 1 | 4
Finally you could query the tables like so
SELECT TOP 10 m.Manganame as link,
m.Manganame,
m.cover,
m.othername,
FROM om_manga as m INNER JOIN
om_chapter as c ON m.ID = c.mangaID
WHERE m.active = 1 AND c.active = 1
ORDER BY m.ID DESC

Answer 3

Why not a simple join?
SELECT om_chapter.manganame, cover, othername
FROM om_chapter
JOIN om_manga ON om_chapter.manganame = om_manga=manganame
WHERE om_chapter.Active = 1 AND om_manga.Active = 1
unless I'm misreading your version.

Answer 4

Use a left outer join (and lose the sub-queries, and the back-quotes):
SELECT c.manganame AS link,
m.manganame AS manganame,
m.cover AS cover,
m.othername AS `othername
FROM om_chapter AS c
LEFT JOIN om_manga AS m
ON c.manganame = m.manganame
WHERE c.Active = '1'
AND c.id IN (SELECT MAX(o.id)
FROM om_chapter AS o
WHERE o.active = 1
GROUP BY o.manganame)
ORDER BY c.id DESC LIMIT 10
Were it my query, I'd probably select 'c.id AS id' too.