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The problem with many many SQL queries

I have three tables: videos, videos_categories and categories.

The tables look like this:

videos: video_id, title, etc...
videos_categories: video_id, category_id
categories: category_id, name, etc...

In my application, I allow the user to multi-select categories. When they do, I need to return all the videos that are in each selected category .

I ended up with this:

SELECT * FROM videos WHERE video_id IN (
    SELECT c1.video_id FROM videos_categories AS c1
    JOIN c2.videos_categories AS c2
    ON c1.video_id = c2.video_id
    WHERE c1.category_id = 1 AND c2.category_id = 2
)

But for each category I add to the multi-select, I have to add a connection to my inner choice:

SELECT * FROM videos WHERE video_id IN (
    SELECT c1.video_id FROM videos_categories AS c1
    JOIN videos_categories AS c2
    ON c1.video_id = c2.video_id
    JOIN videos_categories AS c3
    ON c2.video_id = c3.video_id
    WHERE c1.category_id = 1 AND c2.category_id = 2 AND c3.category_id = 3
)

I cannot help but feel that this is really the wrong way to do this, but I am blocked out trying to figure out how to do this.

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3 answers

if it is a primary key:

 videos_categories: video_id, category_id

GROUP BY HAVING , :

SELECT
    * 
    FROM videos 
    WHERE video_id IN (SELECT 
                           video_id
                           FROM videos_categories
                           WHERE category_id IN (1,2,3)
                           GROUP BY video_id
                           HAVING COUNT(video_id)=3
                      )
+6

FOR XML PATH:

--Sample data
CREATE TABLE Video
    (
    VideoID int,
    VideoName varchar(50)
    )

CREATE TABLE Videos_Categories
    (
    VideoID int,
    CategoryID int
    )

INSERT  Video(VideoID, VideoName)
SELECT  1, 'Indiana Jones'
UNION ALL
SELECT  2, 'Star Trek'

INSERT Videos_Categories(VideoID, CategoryID)
SELECT 1, 1
UNION ALL
SELECT 1, 2
UNION ALL
SELECT 1, 3
UNION ALL
SELECT 2, 1
GO

--The query
;WITH   GroupedVideos
AS
(
SELECT  v.*,
        SUBSTRING(
                    (SELECT  (', ') + CAST(vc.CategoryID AS varchar(20))
                    FROM     Videos_Categories AS vc
                    WHERE    vc.VideoID = v.VideoID
                    AND      vc.CategoryID IN (1,2)
                    ORDER BY vc.CategoryID
                    FOR XML PATH('')), 3, 2000) AS CatList
FROM    Video AS v
)

SELECT  *
FROM    GroupedVideos
WHERE   CatList = '1, 2'

( - )

Try

WHERE c1.category_id IN (1,2,3)


...
FROM videos v
JOIN Vedeos_categories vc ON v.video_id = vc.video_id
WHERE vc.category_id IN (1,2,3)

.

: ( , ):

SELECT * 
FROM videos 
WHERE video_id IN 
(    SELECT c1.video_id 
FROM videos_categories AS c1
WHERE c1.category_id = IN (1,2,3))


SELECT *
FROM videos v
JOIN Vedeos_categories vc ON v.video_id = vc.video_id
WHERE vc.category_id IN (1,2,3)
0

SQL- ,

(, , ), temp .

CREATE TEMPORARY TABLE query_categories(category_id int);
INSERT INTO query_categories(category_id) VALUES(1);
INSERT INTO query_categories(category_id) VALUES(2);
INSERT INTO query_categories(category_id) VALUES(3);

SELECT * FROM videos v WHERE video_id IN (
  SELECT video_id FROM video_categories vc JOIN query_categories q ON vc.category_id = qc.category_id
  GROUP BY video_id
  HAVING COUNT(*) = 3
)

-, . temp "category_id IN (...)" .

0

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