Parse delimited column into multiple records

Question

Parse delimited column into multiple records

Stef Teal

SSCrazy

Points: 2382
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January 19, 2007 at 3:44 pm

#115902

What is the best way to take 30,000 records with a delimited Outcome field like the following….
PatientId           Outcome
180460             “Observation initiated/increased; Laboratory tests performed; Drug therapy initiated/changed”
And insert multiple recs into another table, one rec for each of the semi-colon delimited values, such as:
PatientId           Outcome
180460             Observation initiated/increased
180460              Laboratory tests performed
180460              Drug therapy initiated/changed

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Russel Loski SSCertifiable Points: 7059 More actions · Answer 1

Can I always split on the semicolon? What is the maximum number of semicolons in a field? Is this something that you want to do once and then not again or is this part of a query that you will be running multiple times and need it have reasonable performance?

Russel Loski, MCSE Business Intelligence, Data Platform

Sergiy SSC Guru Points: 110208 More actions · Answer 2

Just posted the function here:

http://www.sqlservercentral.com/forums/shwmessage.aspx?forumid=8&messageid=338231

_____________
Code for TallyGenerator

Jeff Moden SSC Guru Points: 1004313 More actions · Answer 3

Stef,

These types of problems are incredibly simple if you have the right kind of tools. Fortunately, there is one tool that has tremendous utility as just such a tool. It is called a "Tally" table, consists of a single well-indexed column of numbers, and has many, many uses including solving problems like these. If you don't already have one, now is the time to make one... here's how...

--===== Create and populate the Tally table on the fly

SELECT TOP 11000 --equates to more than 30 years of dates when needed

IDENTITY(INT,1,1) AS N

INTO dbo.Tally

FROM Master.dbo.SysColumns sc1,

Master.dbo.SysColumns sc2

--===== Add a Primary Key to maximize performance

ALTER TABLE dbo.Tally

ADD CONSTRAINT PK_Tally_N PRIMARY KEY CLUSTERED (N)

--===== Allow the general public to use it

GRANT SELECT ON dbo.Tally TO PUBLIC

You only need to make it once... it should be a permanent table in your arsenal of SQL tools.

Because I always like to test these things, here's how I made 30,000 rows of test data. Granted, the data is highly duplicated, but it will suffice for this test... you have real data so you won't need to create this table...

--===== Conditionally drop and recreate a test table to simulate Stef's original table -- (creates 30,000 rows) -- IF OBJECT_ID('OriginalTable') IS NOT NULL -- DROP TABLE OriginalTable
SELECT TOP 30000 ParentID = IDENTITY(INT,180000,1), Outcome = CAST('Observation initiated/increased; Laboratory tests performed; Drug therapy initiated/changed' AS VARCHAR(400)) INTO OriginalTable FROM Master.dbo.SysColumns sc1, Master.dbo.SysColumns sc2
ALTER TABLE OriginalTable ADD PRIMARY KEY (ParentID)

Ok... here's the code that does the trick. I do it only as a SELECT but you could very easily change it to an INSERT/SELECT to get the table you asked for...

--===== Split the original table data into a new normalized table SELECT ParentID, LTRIM(SUBSTRING(+ot.Outcome,t.N+1,CHARINDEX(';',ot.Outcome,t.N+1)-t.N-1)) AS OutCome FROM (SELECT ParentID,';'+Outcome+';' AS OutCome FROM OriginalTable) ot, dbo.Tally t WHERE t.N < LEN(ot.Outcome) AND SUBSTRING(ot.Outcome,t.n,1)=';'

The above code should take about 5 seconds to run. Obviously, you need to change "OriginalTable" to the name of your actual table. Write back if you have any questions...

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)