SQL query to split a column based on hardcoded values - sql

Question

I have a table eg assume this setup
table MyTable has various columns Id, UserId, col1, col2 col3 including column called Stuff.
I want to output certain Columns from MyTable with a query
but i want to split the 'Stuff' column such that 2 new columns are shown in the query
I can define the categories hardcoded, im not sure how this can be represented in sql
Categoy1 = "alpha, bravo, delta, gamma';
Categoy2 = "charlie, echo, hotel';
MyTable
ID | UserID | Stuff | Other Cols....
----------------------------------------------------------
1 1 alpha
2 2 hotel
3 1 charlie
4 1 echo
5 1 gamma
6 2 bravo
7 2 delta
i want the select query to show
UserId | Category1 | Catergory2
----------------------------------------------------------
1 alpha, gamma charlie, echo
---------------------------------------------------------
2 bravo, delta hotel
----------------------------------------------------------
i.e produce 2 columns split based on whether the stuff column contains an item from category1 or category2
based on a distinct userId the categories content can be comma separated as hown above
Please can you show how this can be done
Hope this makes sense.
Thanks

Answer 1

You can use the xml extensions to concatenate your strings, then just hard code the categories into each subquery:
CREATE TABLE #T (ID INT, UserID INT, [Stuff] VARCHAR(300))
INSERT #T VALUES
(1, 1, 'alpha'),
(2, 2, 'hotel'),
(3, 1, 'charlie'),
(4, 1, 'echo'),
(5, 1, 'gamma'),
(6, 2, 'bravo'),
(7, 2, 'delta');
SELECT UserID,
[Category1] = STUFF(( SELECT ', ' + [Stuff]
FROM #T t2
WHERE [Stuff] IN ('alpha', 'bravo', 'delta', 'gamma')
AND t.UserID = t2.UserID
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)'), 1, 2, ''),
[Category2] = STUFF(( SELECT ', ' + [Stuff]
FROM #T t2
WHERE [Stuff] IN ('charlie', 'echo', 'hotel')
AND t.UserID = t2.UserID
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)'), 1, 2, '')
FROM ( SELECT DISTINCT UserID
FROM #T
) t
Example on SQL Fiddle
You could define your categories at the start in a CTE (Categories) for improved readibility:
WITH Categories AS
( SELECT Category, Name
FROM (VALUES
(1, 'alpha'),
(1, 'bravo'),
(1, 'delta'),
(1, 'gamma'),
(2, 'charlie'),
(2, 'echo'),
(2, 'hotel')
) t (Category, Name)
), Data AS
( SELECT UserID, [Stuff], Category
FROM T
INNER JOIN Categories c
ON c.Name = T.[Stuff]
)
SELECT UserID,
[Category1] = STUFF(( SELECT ', ' + [Stuff]
FROM Data t2
WHERE Category = 1
AND t.UserID = t2.UserID
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)'), 1, 2, ''),
[Category2] = STUFF(( SELECT ', ' + [Stuff]
FROM Data t2
WHERE Category = 2
AND t.UserID = t2.UserID
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)'), 1, 2, '')
FROM ( SELECT DISTINCT UserID
FROM T
) t
Example on SQL Fiddle

Answer 2

My try, the technique I learned from Stack Overflow!... Please check:
DECLARE #Categoy1 NVARCHAR(MAX) = 'alpha, bravo, delta, gamma',
#Categoy2 NVARCHAR(MAX) = 'charlie, echo, hotel'
SELECT
UserID,
STUFF((SELECT ', ' + display_term
FROM sys.dm_fts_parser('"'+ ',' + #Categoy1 + '"', 1033, NULL, 0) INNER JOIN
YourTable T on display_term=[Stuff]
WHERE T.UserID= x.UserID
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)'), 1, 2, '') Category1,
STUFF((SELECT ', ' + display_term
FROM sys.dm_fts_parser('"'+ ',' + #Categoy2 + '"', 1033, NULL, 0) INNER JOIN
YourTable T on display_term=[Stuff]
WHERE T.UserID= x.UserID
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)'), 1, 2, '') Category2
FROM YourTable x
GROUP BY UserID