I am writing a query
SELECT
`user_bookmarks`.`id` as `user_bookmark_id`,
`bookmark_id`,
`user_bookmarks`.`user_id`,
`bookmark_url`,
`bookmark_website`,
`bookmark_title`,
`bookmark_preview_image`,
`bookmark_popularity`,`category_id`,
`category_name`,
`pdf_txt_flag`,
`youtube_video`,
`content_preview`,
`snapshot_preview_image`,
`mode`
FROM
`user_bookmarks`
left join `bookmarks`
on `user_bookmarks`.`bookmark_id` = `bookmarks`.`id`
left join `categories`
on `user_bookmarks`.`category_id` = `categories`.`id`
WHERE
`category_id` IN(164,170,172)
LIMIT 0, 6
it is fetching first 6 bookmarks. But i want it will fetch 6 bookmarks from each category. Can we do this in mysql itself.
Please adivce..
Thanks
You can use a rank query to give a rank for each category and filter it with your desired no of records per category below query will give you 6 records from each category
SELECT t.* FROM
(SELECT
`user_bookmarks`.`id` AS `user_bookmark_id`,
`bookmark_id`,
`user_bookmarks`.`user_id`,
`bookmark_url`,
`bookmark_website`,
`bookmark_title`,
`bookmark_preview_image`,
`bookmark_popularity`,
`category_id`,
`category_name`,
`pdf_txt_flag`,
`youtube_video`,
`content_preview`,
`snapshot_preview_image`,
`mode` ,
#r:= CASE WHEN category_id = #g THEN #r+1 ELSE #r:=1 END `rank` ,
#g:=category_id
FROM
`user_bookmarks`
LEFT JOIN `bookmarks`
ON `user_bookmarks`.`bookmark_id` = `bookmarks`.`id`
LEFT JOIN `categories`
ON `user_bookmarks`.`category_id` = `categories`.`id`
JOIN (SELECT #r:=0,#g:=0) t1
WHERE `category_id` IN (164, 170, 172)
ORDER BY category_id
) t
WHERE t.rank <=6
You have to use the GROUP BY statement, but you cannot have a limit per each one of them.
I suggest you look at this question with answer in Old post and read the article mentioned in the post.
Related
I've been trying to figure this one out for days but can't come up with a solution.
Here are the table schemes.
This is my current query.
SELECT DISTINCT `address`, `order`.`id`
FROM `order`, `ordered_articles`
WHERE `order`.`id` = `f_order_id`
AND `Status` > 1
AND `Status` <4;
The problem is that the query returns as long as there is one article with status bigger than 1. I need a query where all the articles of that order have a status bigger than 1.
You can do it with NOT EXISTS:
SELECT o.`address`, o.`id`
FROM `order` o
WHERE NOT EXISTS (
SELECT 1 FROM `ordered_articles`
WHERE `f_order_id` = o.`id`
AND (`Status` <= 1 OR `Status` >= 4 )
);
or:
SELECT o.`address`, o.`id`
FROM `order` o INNER JOIN `ordered_articles` i
ON i.`f_order_id` = o.`id`
GROUP BY o.`address`, o.`id`
HAVING SUM(`Status` <= 1 OR `Status` >= 4) = 0;
How use custom alias field from select fields in join?
SELECT LOWER(CONCAT(`ufn`.`value`, '.', `uln`.`value`, CAST(RAND()*1e6 AS UNSIGNED))) AS `newlogin`
FROM `user_firstname` AS `ufn`
INNER JOIN `user_lastname` AS `uln`
LEFT JOIN `user` AS `u` ON `u`.`login` = `newlogin`
WHERE `ufn`.`sex` = 'male' AND `u`.`id` IS NULL
ORDER BY RAND()
LIMIT 1
Result: sql-error.png
EDIT:
My solution, but, ...:
SELECT #newlogin
FROM (
SELECT #newlogin := LOWER(CONCAT(`ufn`.`value`, '.', `uln`.`value`, CAST(RAND()*1e6 AS UNSIGNED)))
FROM `user_firstname` AS `ufn`
INNER JOIN `user_lastname` AS `uln`
WHERE `ufn`.`sex` = 'male'
ORDER BY RAND()
LIMIT 1
) AS `ufnX`
LEFT JOIN `user` AS `u` ON `u`.`login` = #newlogin
WHERE `u`.`id` IS NULL
Create the new login in a subquery and join it in:
SELECT LOWER(CONCAT(`ufn`.`value`, '.', `uln`.`value`, nl.num)) AS newlogin
FROM (SELECT CAST(RAND()*1e6 AS UNSIGNED))) AS num
) nl CROSS JOIN
`user_firstname` ufn CROSS JOIN
`user_lastname` uln LEFT JOIN
`user` u
ON `u`.`login` = LOWER(CONCAT(ufn.`value`, '.', uln.`value`, nl.num))
WHERE `ufn`.`sex` = 'male' AND `u`.`id` IS NULL
ORDER BY RAND()
LIMIT 1;
Note I replaced the INNER JOIN with CROSS JOIN. INNER JOIN with no ON makes no sense.
EDIT:
You seem to want to test multiple values to get a match. You could try putting the comparison in the HAVING clause. That clause can reference columns in the SELECT:
SELECT LOWER(CONCAT(ufn.`value`, '.', uln.`value`, CAST(RAND()*1e6 AS UNSIGNED))) AS newlogin
FROM user_firstname` ufn CROSS JOIN
`user_lastname` uln
WHERE `ufn`.`sex` = 'male'
HAVING NOT EXISTS (SELECT 1
FROM user u
WHERE u.login = newlogin
)
ORDER BY RAND()
LIMIT 1;
I have following Mysql query
SELECT c.`id`
,c.`category_name`
,c.`category_type`
,c.bookmark_count
,f.category_id cat_id
,f.unfollow_at
,(
CASE WHEN c.id = f.follower_category_id
THEN (
SELECT count(`user_bookmarks`.`id`)
FROM `user_bookmarks`
WHERE (`user_bookmarks`.`category_id` = cat_id)
AND ((`f`.`unfollow_at` > `user_bookmarks`.`created_at`) || (`f`.`unfollow_at` = '0000-00-00 00:00:00'))
)
ELSE 0 END
) counter
,c.id
,f.follower_category_id follow_id
,c.user_id
FROM categories c
LEFT JOIN following_follower_categories f ON f.follower_category_id = c.id
WHERE c.user_id = 26
ORDER BY `category_name` ASC
and here is output what i am getting after execuation
now i just want to count . here i have field id having value 172 against it i have counter 30,3, 2 and Bookmark_count is 4( i need to include only once)
and i am accepting output for id 172 is 30+3+2+4(bookmark_count only once).
I am not sure how to do this.
Can anybody help me out
Thanks a lot
The following may be the most inefficient query for that purpose, but I added a cover to your query in order to hint at grouping the results.
(I removed the second c.id, and my example may have errors since I couldn't try it.)
SELECT `id`,
`category_name`,
`category_type`,
max(`bookmark_count`),
`cat_id`,
`unfollow_at`,
sum(`counter`)+max(`bookmark_count`) counter,
follow_id`, `user_id`
FROM
(SELECT c.`id`
,c.`category_name`
,c.`category_type`
,c.bookmark_count
,f.category_id cat_id
,f.unfollow_at
,(
CASE WHEN c.id = f.follower_category_id
THEN (
SELECT count(`user_bookmarks`.`id`)
FROM `user_bookmarks`
WHERE (`user_bookmarks`.`category_id` = cat_id)
AND ((`f`.`unfollow_at` > `user_bookmarks`.`created_at`) || (`f`.`unfollow_at` = '0000-00-00 00:00:00'))
)
ELSE 0 END
) counter
,f.follower_category_id follow_id
,c.user_id
FROM categories c
LEFT JOIN following_follower_categories f ON f.follower_category_id = c.id
WHERE c.user_id = 26)
GROUP BY `id`, `category_name`, `category_type`, `cat_id`, `unfollow_at`, `follow_id`, `user_id`
ORDER BY `category_name` ASC
I wish to select results across several tables, but I only want to return rows based on the COUNT() result of joined SELECT query.
Here's how the query looks at the moment:
SELECT `s`.`venue_id` AS `id`,
CONCAT(`u`.`First_name`, ' ', `u`.`Surname`) AS `user_name`,
`u`.`avatar` AS `avatar`,
`u`.`facebookId` AS `fid`,
`x`.`imgs` AS `num_imgs`
FROM `new_shortlists_venues` `s`
INNER JOIN `new_shortlists` ON `new_shortlists`.`id` = `s`.`list_id`
INNER JOIN `users` `u` ON `u`.`id` = `new_shortlists`.`bride_id`
LEFT JOIN (SELECT `listing_id`, COUNT(*) `imgs` FROM `listingsImages`) `x` ON `s`.`venue_id` = `x`.`listing_id`
WHERE `new_shortlists`.`venues` > 4
AND `new_shortlists`.`bride_id` != 0
GROUP BY `s`.`list_id`
ORDER BY `s`.`date_added` DESC
LIMIT 6
For some reason, the query returns NULL for num_imgs. Essentially, I'd like to select only records which have at least 4 records in the listingsImages table.
Please note that this is for a legacy system, and I didn't design the DB! As a result, I have now option to change the schema.
You left off the GROUP BY of your subquery. Your current query is returning COUNT(*) associated with a random listing_id. Add GROUP BY listing_id and you should return the correct counts.
SELECT `s`.`venue_id` AS `id`,
CONCAT(`u`.`First_name`, ' ', `u`.`Surname`) AS `user_name`,
`u`.`avatar` AS `avatar`,
`u`.`facebookId` AS `fid`,
`x`.`imgs` AS `num_imgs`
FROM `new_shortlists_venues` `s`
INNER JOIN `new_shortlists` ON `new_shortlists`.`id` = `s`.`list_id`
INNER JOIN `users` `u` ON `u`.`id` = `new_shortlists`.`bride_id`
LEFT JOIN (SELECT `listing_id`, COUNT(*) `imgs`
FROM `listingsImages`
GROUP BY `listing_id`) `x` ON `s`.`venue_id` = `x`.`listing_id`
WHERE `new_shortlists`.`venues` > 4
AND `new_shortlists`.`bride_id` != 0
GROUP BY `s`.`list_id`
ORDER BY `s`.`date_added` DESC
LIMIT 6
And to return those with at least 4 records, just add that constraint to your WHERE criteria:
AND `x`.`imgs` >= 4
This might be the culprit:
ON `s`.`venue_id` = `x`.`listing_id`
I have the following MySQL query, which produces the result I want:
SELECT
`l`.`status`,
`l`.`acquired_by`, `a`.`name` AS 'acquired_by_name',
`l`.`researcher`, `r`.`name` AS 'researcher_name',
`l`.`surveyor`, `s`.`name` AS 'surveyor_name'
FROM `leads` `l`
LEFT JOIN (
SELECT '0' AS 'id', 'Unassigned' AS 'name'
UNION ALL
SELECT `id`, `name`
FROM `web_users`
) `r` ON `r`.`id` = `l`.`researcher`
LEFT JOIN (
SELECT '0' AS 'id', 'Unassigned' AS 'name'
UNION ALL
SELECT `id`, `name`
FROM `web_users`
) `s` ON `s`.`id` = `l`.`surveyor`
LEFT JOIN (
SELECT '0' AS 'id', 'Unassigned' AS 'name'
UNION ALL
SELECT `id`, `name`
FROM `web_users`
) `a` ON `a`.`id` = `l`.`acquired_by`
WHERE `l`.`id` = 566
But as you can see, it has the same sub-query in it three times. Is there any way to execute this query once and store the result, so I can LEFT JOIN with the cached results instead of executing the same query three times?
I have tried storing it in a variable:
SET #usercache = (
SELECT '0' AS 'id', 'Unassigned' AS 'name'
UNION ALL
SELECT `id`, `name`
FROM `web_users`
)
...but this gives me an error:
1241 - Operand should contain 1 column(s)
...and some Googling on this error has left me none the wiser.
Does anyone know how I can make this query more efficient? Or am I just worrying about something that doesn't matter anyway?
I am using PHP/MySQLi if it makes any difference.
Do you really need the subqueries? How about this:
SELECT
`l`.`status`,
`l`.`acquired_by`, COALESCE(`a`.`name`, 'Unassigned') AS 'acquired_by_name',
`l`.`researcher`, COALESCE(`r`.`name`, 'Unassigned') AS 'researcher_name',
`l`.`surveyor`, COALESCE(`s`.`name`, 'Unassigned') AS 'surveyor_name'
FROM `leads` `l`
LEFT JOIN `web_users` `r` ON `r`.`id` = `l`.`researcher`
LEFT JOIN `web_users` `s` ON `s`.`id` = `l`.`surveyor`
LEFT JOIN `web_users` `a` ON `a`.`id` = `l`.`acquired_by`
WHERE `l`.`id` = 566
you cannot run it once - you are actually using it three times to get three different results...