cat use min as condition
the where statement is where it breaks but i cant fix it
select category, count(*) as number_of_cats
from books
where number_of_cats > min(number_of_cats)
group by category
order by category;
Having + sub-query
select category, count(*) as number_of_books
from books
group by category
having count(*) > -- check the one whose count is STRICTLY greater then minimum
( select min (st.t) -- find the minimum of all categories
from
( select count(*) as t --find the count for all categories
from books
group by category
) st -- an alias to avoid parsing errors
)
Another option, but with this solution in case of ex-aequo only first category is removed:
select select category, count(*) as number_of_books
from books
where category not in (select bb.category
from books bb
group by bb.category
order by count(*) asc
limit 1)
group by category
You could use common table expressions here, e.g.:
WITH CategoryCount AS (
SELECT
category,
COUNT(*) AS number_of_books
FROM
books
GROUP BY
category),
MinBooks AS (
SELECT
MIN(number_of_books) AS min_number_of_books
FROM
CategoryCount)
SELECT
cc.*
FROM
CategoryCount cc
CROSS JOIN MinBooks m
WHERE
cc.number_of_books > m.min_number_of_books;
Related
Let's say I have a table films(film, category).
I want to find the category with the most films. How do I do that without using LIMIT?
I suppose I could do something like this:
SELECT category
FROM
(SELECT category, COUNT(*) AS num
FROM films
GROUP BY category) AS T1
WHERE num =
(SELECT MAX(num)
FROM
(SELECT category, COUNT(*) AS num
FROM films
GROUP BY category) AS T2)
But is there a more elegant way of doing that? Preferably one where I don't have to write the same subquery multiple times?
Thanks!
(And if you're wondering why I can't use LIMIT, it's for homework)
you could do it using a variable to create a row number:
SELECT category
FROM
(
SELECT
category
COUNT(*) as NumOfFiles
,(#rn:= #rn + 1) as RowNumber
FROM
Films f
CROSS JOIN (SELECT #rn:=0) vars
GROUP BY
category
ORDER BY
COUNT(*) DESC
) t
WHERE
t.RowNumber = 1
Having the following tables
Post(*id, name, description, cat, publish_date)
Category(*id, name)
It is possible in ONE query to get (max) the first N element of each different category?
Assuming that N=3, i'd need the following result:
Result set:
["1", "Name1","Descr","cat1"]
["2", "Name1","Descr","cat1"]
["3", "Name1","Descr","cat1"]
["10","Name1","Descr","cat2"]
["20","Name1","Descr","cat2"]
["22","Name1","Descr","cat2"]
["25","Name1","Descr","cat3"]
["30","Name1","Descr","cat3"]
["19","Name1","Descr","cat3"]
And so on.
I need this, to get the first N article of EACH category, with one query (so without ask for a specific category but for all category in table)
It is possible? If yes what's the right query?
This query will do what you need. If any category has less than 3 post it will still work.
SELECT P.id,P.name,P.description,C.name
FROM Post P
LEFT JOIN Category C
ON P.type = C.id
WHERE FIND_IN_SET(P.id,
(
SELECT GROUP_CONCAT(ids) FROM
(SELECT SUBSTRING_INDEX(GROUP_CONCAT(id),',',3) as ids
FROM Post
GROUP BY type
) AS foo
GROUP BY ''
)
)
Here is a working SQL Fiddle
UPDATE
In response to your comment and updated question:
SELECT P.id,P.name,P.description,P.publish_date,C.name
FROM Post P
LEFT JOIN Category C
ON P.type = C.id
WHERE FIND_IN_SET(P.id,
(
SELECT GROUP_CONCAT(ids) FROM
(SELECT SUBSTRING_INDEX(GROUP_CONCAT(id ORDER BY publish_date DESC),',',3) as ids
FROM Post
GROUP BY type
) AS foo
GROUP BY ''
)
)
You can use UNION to join multiple queries into one. This assumes that you know what type you are selecting for each set.
SELECT * FROM
(
SELECT * FROM T1 WHERE type='Type1' ORDER BY id DESC LIMIT 3
) DUMMY1
UNION ALL
SELECT * FROM
(
SELECT * FROM T1 WHERE type='Type2' ORDER BY id DESC LIMIT 3
) DUMMY2
UNION ALL
SELECT * FROM
(
SELECT * FROM T1 WHERE type='Type3' ORDER BY id DESC LIMIT 3
) DUMMY3
The DUMMY table aliases are needed to allow ordering within each subquery.
I use mysql. My table look like this:
Last I try to use this query
SELECT * FROM movie GROUP BY `group` HAVING cateogry = 'TV'
I want with this query result as: show all but only GROUP BY TV category, where category = 'TV'
I want this Result
But my query give me this result (HAVING in query work as WHERE clouse)
IF I use this QUERY
SELECT * FROM movie GROUP BY `group`
It give me this result
I want -> QUERY -> GROUP BY group (ID no 9 and ID 1,2,3 treat as different group name)
IF group has all same values BUT category='movie' (RETURN ALL ROWS
group by NOT APPLY)
IF group has all same values BUT category='TV' (RETURN 1 ROW group by APPLY)
You seem to want this query:
select m.*
from movie m join
(select `group`, min(id) as minid
from movie
group by `group`
) g
on m.id = g.minid;
SELECT min(ID) as ID, min(Name), `group`, Category
FROM movie
GROUP BY `group`, Category
ORDER BY ID
Have you tried the below? I think you are pretty close. As when you are grouping your 'group' t. You are also grouping the one whose category is movie as well. So you just need to create a separate group Category.
SELECT * FROM movie
WHERE group = 't'
GROUP BY group, Category
ORDER BY ID
My table is
f1(drinker,shop)
The table has a list of drinkers and the shops which they visit.I need to find the most popular shop.I know I can do a simple group by of shops and order it in a descending way and limit the results to 1 but my doubt is what if two or more shop have the same number of drinkers in that case my query fails.I can't use limit 2 or 3 because I want a general working query and not a one specific to the data.I am running out of ideas.
Note:
Please don't show this way:
select shop from f1 group by shop order by count(*) desc limit 1
In that case, you have to compare the counts. Not so pretty with a group by query:
select shop
from f1
group by shop
having count(*) = (select max(cnt)
from (select count(*) as cnt
from f1
group by shop
) s
);
You could also do this as a subquery:
select shop
from f1 join
(select count(*) as cnt
from f1
group by shop
order by count(*) desc
limit 1
) f1max
group by shop
having count(*) = max(f1max.cnt);
I have this table:
Movies (ID, Genre)
A movie can have multiple genres, so an ID is not specific to a genre, it is a many to many relationship. I want a query to find the total number of movies which have at exactly 4 genres. The current query I have is
SELECT COUNT(*)
FROM Movies
GROUP BY ID
HAVING COUNT(Genre) = 4
However, this returns me a list of 4's instead of the total sum. How do I get the sum total sum instead of a list of count(*)?
One way would be to use a nested query:
SELECT count(*)
FROM (
SELECT COUNT(Genre) AS count
FROM movies
GROUP BY ID
HAVING (count = 4)
) AS x
The inner query gets all the movies that have exactly 4 genres, then outer query counts how many rows the inner query returned.
SELECT COUNT(*)
FROM (SELECT COUNT(*)
FROM movies
GROUP BY id
HAVING COUNT(genre) = 4) t
Maybe
SELECT count(*) FROM (
SELECT COUNT(*) FROM Movies GROUP BY ID HAVING count(Genre) = 4
) AS the_count_total
although that would not be the sum of all the movies, just how many have 4 genre's.
So maybe you want
SELECT sum(
SELECT COUNT(*) FROM Movies GROUP BY ID having Count(Genre) = 4
) as the_sum_total
What about:
SELECT COUNT(*) FROM (SELECT ID FROM Movies GROUP BY ID HAVING COUNT(Genre)=4) a