how to split a string column into 4 string columns? - sql-server-2008

Question

I have definition column of a medication. I want the definition to be split into [product name(PN)], [doseform(DF)], [total dose(TD)] and [units].
Eg:
BENADRYL: MYLANTA 1:1 SOLUTION(Benadryl mylanta(PN),Sol(DF),1:1(TD),NULL(units))
MASK AND SPACER (Mark and Spacer(PN),NUll,NUll,NUll)
BL VITAMIN B-6 50 MG TABS(BL Vitamin(PN),Tabs(DF),50(TD),MG(Units))

Answer 1

I've made a few assumptions about your data. 1 is that the first opening bracket begins the definition ie. there are no brackets in the name before the definition. I am also assuming the the product definition structure will not change.
So, to get to your answer, I have used a modified split string function. I used this one as a base: T-SQL split string
The difference here is that the function will return a 2 column table so we can identify the definition parts
CREATE FUNCTION dbo.splitstring_custom
(
#stringToSplit VARCHAR(MAX)
)
RETURNS #returnList TABLE
(
[Type] [nvarchar](20)
,[Name] [nvarchar](500)
)
AS
BEGIN
DECLARE #name NVARCHAR(255)
DECLARE #pos INT
DECLARE #colidx INT = 1
WHILE CHARINDEX(',', #stringToSplit) > 0
BEGIN
SELECT #pos = CHARINDEX(',', #stringToSplit)
SELECT #name = SUBSTRING(#stringToSplit, 1, #pos - 1)
INSERT INTO #returnList
SELECT CASE WHEN #colidx = 1 THEN 'Product Name'
WHEN #colidx = 2 THEN 'Dose Form'
WHEN #colidx = 3 THEN 'Total Dose'
WHEN #colidx = 4 THEN 'Units'
END
,#name
SELECT #stringToSplit = SUBSTRING(#stringToSplit, #pos + 1, LEN(#stringToSplit) - #pos)
SET #colidx += 1
END
INSERT INTO #returnList
SELECT CASE WHEN #colidx = 1 THEN 'Product Name'
WHEN #colidx = 2 THEN 'Dose Form'
WHEN #colidx = 3 THEN 'Total Dose'
WHEN #colidx = 4 THEN 'Units'
END
,#stringToSplit
RETURN
END
Then we get the relevant part of the definition using some string manipulation:
SUBSTRING(medication, CHARINDEX('(', medication) + 1, LEN(medication) - (CHARINDEX('(', medication) + 1))
Then PIVOT the results to flatten it out:
DECLARE #t TABLE (id varchar(20), medication varchar(100))
INSERT INTO #t VALUES ('BENADRYL', 'BENADRYL: MYLANTA 1:1 SOLUTION(Benadryl mylanta(PN),Sol(DF),1:1(TD),NULL(units))')
INSERT INTO #t VALUES ('MASK', 'MASK AND SPACER (Mark and Spacer(PN),NULL,NULL,NULL)')
INSERT INTO #t VALUES ('BL VITAMIN', 'BL VITAMIN B-6 50 MG TABS(BL Vitamin(PN),Tabs(DF),50(TD),MG(Units))')
SELECT id, [Product Name], [Dose Form], [Total Dose], [Units]
FROM (SELECT id, Type, Name
FROM #t t
CROSS APPLY dbo.splitstring_custom(SUBSTRING(medication, CHARINDEX('(', medication) + 1, LEN(medication) - (CHARINDEX('(', medication) + 1)))
) X PIVOT ( MAX(Name) FOR TYPE IN ([Product Name], [Dose Form], [Total Dose], [Units]) ) pvt