SQL LEFT JOIN to many categories - sql

Question

Suppose the following easy scenario, where a product row gets connected to one primary category, subcategory, and sub-subcategory.
DECLARE #PRODUCTS TABLE (ID int, DESCRIPTION varchar(50), CAT varchar(30), SUBCAT varchar(30), SUBSUBCAT varchar(30));
INSERT #PRODUCTS (ID, DESCRIPTION, CAT, SUBCAT, SUBSUBCAT) VALUES
(1, 'NIKE MILLENIUM', '1', '10', '100'),
(2, 'NIKE CORTEZ', '1', '12', '104'),
(3, 'ADIDAS PANTS', '2', '27', '238'),
(4, 'PUMA REVOLUTION 5', '3', '35', '374'),
(5, 'SALOMON SHELTER CS', '4', '15', '135'),
(6, 'NIKE EBERNON LOW', '2', '14', '157');
DECLARE #CATS TABLE (ID int, DESCR varchar(100));
INSERT #CATS (ID, DESCR) VALUES
(1, 'MEN'),
(2, 'WOMEN'),
(3, 'UNISEX'),
(4, 'KIDS'),
(5, 'TEENS'),
(6, 'BACK TO SCHOOL');
DECLARE #SUBCATS TABLE (ID int, DESCR varchar(100));
INSERT #SUBCATS (ID, DESCR) VALUES
(10, 'FOOTWEAR'),
(12, 'OUTERWEAR'),
(14, 'SWIMWEAR'),
(15, 'HOODIES'),
(27, 'CLOTHING'),
(35, 'SPORTS');
DECLARE #SUBSUBCATS TABLE (ID int, DESCR varchar(100));
INSERT #SUBSUBCATS (ID, DESCR) VALUES
(100, 'RUNNING'),
(104, 'ZIP TOPS'),
(135, 'FLEECE'),
(157, 'BIKINIS'),
(238, 'PANTS'),
(374, 'JOGGERS');
SELECT prod.ID,
prod.DESCRIPTION,
CONCAT(cat1.DESCR, ' > ', cat2.DESCR, ' > ', cat3.DESCR) AS CATEGORIES
FROM #PRODUCTS AS prod
LEFT JOIN #CATS AS cat1 ON cat1.ID = prod.CAT
LEFT JOIN #SUBCATS AS cat2 ON cat2.ID = prod.SUBCAT
LEFT JOIN #SUBSUBCATS AS cat3 ON cat3.ID = prod.SUBSUBCAT;
Now suppose that the foreign keys on #PRODUCTS table aren't just indices to their respective tables. They are comma-separated indices to more than one categories, subcategories, and sub-subcategories like here.
DECLARE #PRODUCTS TABLE (ID int, DESCRIPTION varchar(50), CAT varchar(30), SUBCAT varchar(30), SUBSUBCAT varchar(30));
INSERT #PRODUCTS (ID, DESCRIPTION, CAT, SUBCAT, SUBSUBCAT) VALUES
(1, 'NIKE MILLENIUM', '1, 2', '10, 12', '100, 135'),
(2, 'NIKE CORTEZ', '1, 5', '12, 15', '104, 374'),
(3, 'ADIDAS PANTS', '2, 6', '27, 35', '238, 374');
DECLARE #CATS TABLE (ID int, DESCR varchar(100));
INSERT #CATS (ID, DESCR) VALUES
(1, 'MEN'),
(2, 'WOMEN'),
(3, 'UNISEX'),
(4, 'KIDS'),
(5, 'TEENS'),
(6, 'BACK TO SCHOOL');
DECLARE #SUBCATS TABLE (ID int, DESCR varchar(100));
INSERT #SUBCATS (ID, DESCR) VALUES
(10, 'FOOTWEAR'),
(12, 'OUTERWEAR'),
(14, 'SWIMWEAR'),
(15, 'HOODIES'),
(27, 'CLOTHING'),
(35, 'SPORTS');
DECLARE #SUBSUBCATS TABLE (ID int, DESCR varchar(100));
INSERT #SUBSUBCATS (ID, DESCR) VALUES
(100, 'RUNNING'),
(104, 'ZIP TOPS'),
(135, 'FLEECE'),
(157, 'BIKINIS'),
(238, 'PANTS'),
(374, 'JOGGERS');
SELECT prod.ID,
prod.DESCRIPTION
--CONCAT(cat1.DESCR, ' > ', cat2.DESCR, ' > ', cat3.DESCR) AS CATEGORIES
FROM #PRODUCTS AS prod
--LEFT JOIN #CATS AS cat1 ON cat1.ID = prod.CAT
--LEFT JOIN #SUBCATS AS cat2 ON cat2.ID = prod.SUBCAT
--LEFT JOIN #SUBSUBCATS AS cat3 ON cat3.ID = prod.SUBSUBCAT;
In this case I want to achieve the following:
Be able to retrieve the respective names of the cats, subcats, sub-subcats, ie. for cats '1, 2' be able to retrieve their names (I tried LEFT JOIN #CATS AS cat1 ON cat1.ID IN prod.CAT but it doesn't work)
Create triplets of the corresponding cats, subcats, sub-subcats, ie. for
cats '1, 2'
subcats '12, 17'
sub-subcats '239, 372'
(after retrieving the appropriate names) create pipe-separated category routes like name of cat 1 > name of subcat 12 > name of sub-subcat 239 | name of cat 2 > name of subcat 17 > name of sub-subcat 372
So, for a row like (1, 'NIKE MILLENIUM', '1, 2', '10, 12', '100, 135'),
I would like to get the following result
ID
DESCRIPTION
CATEGORIES
1
NIKE MILLENIUM
MEN > FOOTWEAR > RUNNING # WOMEN > OUTERWEAR > FLEECE (I had to use # as the delimiter of the two triplets because pipe messed with the table's columns)
In case the user stupidly stores more cat IDs than subcat IDs, or sub-subcat IDs, the query should just match the ones that have a corresponding position match, ie for
cats '1, 2'
subcats '12'
sub-subcats '239, 372'
it should just create one triplet, like name of 1 > name of 12 > name of 239

Answer 1

STRING_SPLIT() does not promise to return the values in a specific order, so it won't work in this case as ordinal position matters.
Use OPENJSON() split the string into separate rows to ensure the values are returned in the same order.
OPENJSON() also returns a key field, so you can join on the row number within each grouping. You'll want an INNER JOIN since your requirement is that all values in that "column" must exist.
Use STUFF() to assemble the various cat>subcat>subsubcat values.
DECLARE #PRODUCTS TABLE (ID int, DESCRIPTION varchar(50), CAT varchar(30), SUBCAT varchar(30), SUBSUBCAT varchar(30));
INSERT #PRODUCTS (ID, DESCRIPTION, CAT, SUBCAT, SUBSUBCAT) VALUES
(1, 'NIKE MILLENIUM', '1, 2', '10, 12', '100, 135'),
(2, 'NIKE CORTEZ', '1, 5', '12, 15', '104, 374'),
(3, 'ADIDAS PANTS', '2, 6, 1', '27, 35, 10', '238, 374, 100'),
(4, 'JOE THE PLUMBER JEANS', '1, 5', '27', '238, 374');
DECLARE #CATS TABLE (ID int, DESCR varchar(100));
INSERT #CATS (ID, DESCR) VALUES
(1, 'MEN'),
(2, 'WOMEN'),
(3, 'UNISEX'),
(4, 'KIDS'),
(5, 'TEENS'),
(6, 'BACK TO SCHOOL');
DECLARE #SUBCATS TABLE (ID int, DESCR varchar(100));
INSERT #SUBCATS (ID, DESCR) VALUES
(10, 'FOOTWEAR'),
(12, 'OUTERWEAR'),
(14, 'SWIMWEAR'),
(15, 'HOODIES'),
(27, 'CLOTHING'),
(35, 'SPORTS');
DECLARE #SUBSUBCATS TABLE (ID int, DESCR varchar(100));
INSERT #SUBSUBCATS (ID, DESCR) VALUES
(100, 'RUNNING'),
(104, 'ZIP TOPS'),
(135, 'FLEECE'),
(157, 'BIKINIS'),
(238, 'PANTS'),
(374, 'JOGGERS');
;
with prod as (
SELECT p.ID,
p.DESCRIPTION
--CONCAT(cat1.DESCR, ' > ', cat2.DESCR, ' > ', cat3.DESCR) AS CATEGORIES
, c.value as CatId
, c.[key] as CatKey
, sc.value as SubCatId
, sc.[key] as SubCatKey
, ssc.value as SubSubCatId
, ssc.[key] as SubSubCatKey
FROM #PRODUCTS p
cross apply OPENJSON(CONCAT('["', REPLACE(cat, ', ', '","'), '"]')) c
cross apply OPENJSON(CONCAT('["', REPLACE(subcat, ', ', '","'), '"]')) sc
cross apply OPENJSON(CONCAT('["', REPLACE(subsubcat, ', ', '","'), '"]')) ssc
where c.[key] = sc.[key]
and c.[key] = ssc.[key]
)
, a as (
select p.ID
, p.DESCRIPTION
, c.DESCR + ' > ' + sc.DESCR + ' > ' + ssc.DESCR as CATEGORIES
, p.CatKey
from prod p
inner join #CATS c on c.ID = p.CatId
inner join #SUBCATS sc on sc.ID = p.SubCatId
inner join #SUBSUBCATS ssc on ssc.ID = p.SubSubCatId
)
select DISTINCT ID
, DESCRIPTION
, replace(STUFF((SELECT distinct ' | ' + a2.CATEGORIES
from a a2
where a.ID = a2.ID
FOR XML PATH(''))
,1,2,''), '>', '>') CATEGORIES
from a

Answer 2

Totally separate answer because of the change to older technology. I think my original answer is still good for folks using current SQL Server versions, so I don't want to remove it.
I don't remember where I got the function. When I found it today it was named split_delimiter. I changed the name, added some comments, and incorporated the ability to have a delimiter that is more than one character long.
CREATE FUNCTION [dbo].[udf_split_string](#delimited_string VARCHAR(8000), #delimiter varchar(10))
RETURNS TABLE AS
RETURN
WITH cte10(num) AS ( -- 10 rows
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
)
, cte100(num) AS ( -- 100 rows
SELECT 1
FROM cte10 t1, cte10 t2
)
, cte10000(num) AS ( -- 10000 rows
SELECT 1
FROM cte100 t1, cte100 t2
)
, cte1(num) AS ( -- 1 row per character
SELECT TOP (ISNULL(DATALENGTH(#delimited_string), 0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL))
FROM cte10000
)
, cte2(num) AS ( -- locations of strings
SELECT 1
UNION ALL
SELECT t.num + len(replace(#delimiter, ' ', '_'))
FROM cte1 t
WHERE SUBSTRING(#delimited_string, t.num, len(replace(#delimiter, ' ', '_'))) = #delimiter
)
, cte3(num, [len]) AS (
SELECT t.num
, ISNULL(NULLIF(CHARINDEX(#delimiter, #delimited_string, t.num), 0) - t.num, 8000)
FROM cte2 t
)
SELECT [Key] = ROW_NUMBER() OVER (ORDER BY t.num)
, [Value] = SUBSTRING(#delimited_string, t.num, t.[len])
FROM cte3 t;
GO
DECLARE #PRODUCTS TABLE (ID int, DESCRIPTION varchar(50), CAT varchar(30), SUBCAT varchar(30), SUBSUBCAT varchar(30));
INSERT #PRODUCTS (ID, DESCRIPTION, CAT, SUBCAT, SUBSUBCAT) VALUES
(1, 'NIKE MILLENIUM', '1, 2', '10, 12', '100, 135'),
(2, 'NIKE CORTEZ', '1, 5', '12, 15', '104, 374'),
(3, 'ADIDAS PANTS', '2, 6, 1', '27, 35, 10', '238, 374, 100'),
(4, 'JOE THE PLUMBER JEANS', '1, 5', '27', '238, 374');
DECLARE #CATS TABLE (ID int, DESCR varchar(100));
INSERT #CATS (ID, DESCR) VALUES
(1, 'MEN'),
(2, 'WOMEN'),
(3, 'UNISEX'),
(4, 'KIDS'),
(5, 'TEENS'),
(6, 'BACK TO SCHOOL');
DECLARE #SUBCATS TABLE (ID int, DESCR varchar(100));
INSERT #SUBCATS (ID, DESCR) VALUES
(10, 'FOOTWEAR'),
(12, 'OUTERWEAR'),
(14, 'SWIMWEAR'),
(15, 'HOODIES'),
(27, 'CLOTHING'),
(35, 'SPORTS');
DECLARE #SUBSUBCATS TABLE (ID int, DESCR varchar(100));
INSERT #SUBSUBCATS (ID, DESCR) VALUES
(100, 'RUNNING'),
(104, 'ZIP TOPS'),
(135, 'FLEECE'),
(157, 'BIKINIS'),
(238, 'PANTS'),
(374, 'JOGGERS');
;
with prod as (
SELECT p.ID,
p.DESCRIPTION
, c.value as CatId
, c.[key] as CatKey
, sc.value as SubCatId
, sc.[key] as SubCatKey
, ssc.value as SubSubCatId
, ssc.[key] as SubSubCatKey
FROM #PRODUCTS p
cross apply dbo.udf_split_string(cat, ', ') c
cross apply dbo.udf_split_string(subcat, ', ') sc
cross apply dbo.udf_split_string(subsubcat, ', ') ssc
where c.[key] = sc.[key]
and c.[key] = ssc.[key]
)
, a as (
select p.ID
, p.DESCRIPTION
, c.DESCR + ' > ' + sc.DESCR + ' > ' + ssc.DESCR as CATEGORIES
, p.CatKey
from prod p
inner join #CATS c on c.ID = p.CatId
inner join #SUBCATS sc on sc.ID = p.SubCatId
inner join #SUBSUBCATS ssc on ssc.ID = p.SubSubCatId
)
select DISTINCT ID
, DESCRIPTION
, replace(STUFF((SELECT distinct ' | ' + a2.CATEGORIES
from a a2
where a.ID = a2.ID
FOR XML PATH(''))
,1,2,''), '>', '>') CATEGORIES
from a

Answer 3

Well that should do work, i changed your character ">" for "-" just for see the data more simple.
the design of your tables is not perfect but the first try almost never is.
select mainp.ID, mainp.DESCRIPTION, stuff(ppaths.metapaths, len(ppaths.metapaths),1,'') metalinks
from #PRODUCTS mainp
cross apply(
select
(select
c.DESCR + '-' + sc.DESCR + '-' + sbc.DESCR + '|'
from #PRODUCTS p
cross apply (select row_number() over(order by Value) id, Value from split(p.CAT, ','))cat_ids
inner join #cats c on c.ID = cat_ids.Value
cross apply (select row_number() over(order by Value) id, Value from split(p.SUBCAT, ','))subcat_ids
inner join #SUBCATS sc on sc.ID = subcat_ids.Value
and subcat_ids.id = subcat_ids.id
cross apply (select row_number() over(order by Value) id, Value from split(p.SUBSUBCAT, ','))subsubcat_ids
inner join #SUBSUBCATS sbc on sbc.ID = subsubcat_ids.Value
and subsubcat_ids.id = subcat_ids.id
where p.id = mainp.ID
for xml path('')) metapaths
) ppaths
the link for split function
https://desarrolladores.me/2014/03/sql-server-funcion-split-para-dividir-un-string/