Parsing text to multiple columns - sql

Question

I have a feed that is populating a single text field in a table with statistics.
I need to pull this data into multiple fields in another table
but the strange format makes importing automatically difficult.
The file format is flat text but an example is below:
08:34:52 Checksum=180957248,TicketType=6,InitialUserType=G,InitialUserID=520,CommunicationType=Incoming,Date=26-03-2012,Time=08:35:00,Service=ST,Duration=00:00:14,Cost=0.12
Effectively it's made up of:
[timestamp] [Field1 name]=[Field1 value],[Field2 name]=[Field2 value],[Field4 name]=[Field4 value]...[CR]
All fields are always in the same order but not always present.
Total columns could be anywhere from 5 to 30.
I've tried the below function to translate it which seems to work mostly but seems to randomly skip fields:
Parsing the data:
(SELECT [Data].[dbo].[GetFromTextString] ( 'Checksum=' ,',' ,RAWTEXT)) AS RowCheckSum,
(SELECT [Data].[dbo].[GetFromTextString] ( 'TicketType=' ,',' ,RAWTEXT)) AS TicketType,
And the Function:
CREATE FUNCTION [dbo].[GetFromTextString]
-- Input start and end and return value.
(#uniqueprefix VARCHAR(100),
#commonsuffix VARCHAR(100),
#datastring VARCHAR(MAX) )
RETURNS VARCHAR(MAX) -- Picked Value.
AS
BEGIN
DECLARE #ADJLEN INT = LEN(#uniqueprefix)
SET #datastring = #datastring + #commonsuffix
RETURN (
CASE WHEN (CHARINDEX(#uniqueprefix,#datastring) > 0)
AND (CHARINDEX(#uniqueprefix + #commonsuffix,#datastring) = 0)
THEN SUBSTRING(#datastring, PATINDEX('%' + #uniqueprefix + '%',#datastring)+#ADJLEN, CHARINDEX(#commonsuffix,#datastring,PATINDEX('%' + #uniqueprefix + '%',#datastring))- PATINDEX('%' + #uniqueprefix + '%',#datastring)-#ADJLEN) ELSE NULL END
)
END
Could anyone suggest a better/cleaner way to strip out the data or could someone work out why this formula skips rows?
Any help really appreciated.

Answer 1

NOTE - THE FIRST SOLUTION IS RUBBISH. I HAVE LEFT IN IT FOR HISTORICAL REASONS, BUT A BETTER SOLUTION IS CONTAINED BELOW
I am not even sure if this will be faster than your current method, but it is the way I would approach the issue (If i was forced into an SQL only solution). The first thing that is required is a table valued function that will perform a split function:
CREATE FUNCTION dbo.Split (#TextToSplit VARCHAR(MAX), #Delimiter VARCHAR(MAX))
RETURNS #Values TABLE (Position INT IDENTITY(1, 1) NOT NULL, TextValues VARCHAR(MAX) NOT NULL)
AS
BEGIN
WHILE CHARINDEX(#Delimiter, #TextToSplit) > 0
BEGIN
INSERT #Values
SELECT LEFT(#TextToSplit, CHARINDEX(#Delimiter, #TextToSplit) - 1)
SET #TextToSplit = SUBSTRING(#TextToSplit, CHARINDEX(#Delimiter, #TextToSplit) + 1, LEN(#TextToSplit))
END
INSERT #Values VALUES (#TextToSplit)
RETURN
END
For my example I am working from a temp table #Worklist, you may need to adapt yours accordingly, or you could just insert the relevant data into #Worklist where I have used dummy data:
DECLARE #WorkList TABLE (ID INT IDENTITY(1, 1) NOT NULL, TextField VARCHAR(MAX))
INSERT #WorkList
SELECT '08:34:52 Checksum=180957248,TicketType=6,InitialUserType=G,InitialUserID=520,CommunicationType=Incoming,Date=26-03-2012,Time=08:35:00,Service=ST,Duration=00:00:14,Cost=0.12'
UNION
SELECT '08:34:52 Checksum=180957249,TicketType=5,InitialUserType=H,InitialUserID=521,CommunicationType=Outgoing,Date=27-03-2012,Time=14:27:00,Service=ST,Duration=00:15:12,Cost=0.37'
The main bit of the query is done here. It is quite long, so I have tried to comment it as well as possible. If further clarification is required I can add more comments.
DECLARE #Output TABLE (ID INT IDENTITY(1, 1) NOT NULL, TextField VARCHAR(MAX))
DECLARE #KeyPairs TABLE (WorkListID INT NOT NULL, KeyField VARCHAR(MAX), ValueField VARCHAR(MAX))
-- STORE TIMESTAMP DATA - THIS ASSUMES THE FIRST SPACE IS THE END OF THE TIMESTAMP
INSERT #KeyPairs
SELECT ID, 'TimeStamp', LEFT(TextField, CHARINDEX(' ', TextField))
FROM #WorkList
-- CLEAR THE TIMESTAMP FROM THE WORKLIST
UPDATE #WorkList
SET TextField = SUBSTRING(TextField, CHARINDEX(' ', TextField) + 1, LEN(TextField))
DECLARE #ID INT = (SELECT MIN(ID) FROM #WorkList)
WHILE #ID IS NOT NULL
BEGIN
-- SPLIT THE STRING FIRST INTO ALL THE PAIRS (e.g. Checksum=180957248)
INSERT #Output
SELECT TextValues
FROM dbo.Split((SELECT TextField FROM #WorkList WHERE ID = #ID), ',')
DECLARE #ID2 INT = (SELECT MIN(ID) FROM #Output)
-- FOR ALL THE PAIRS SPLIT THEM INTO A KEY AND A VALUE (USING THE POSITION OF THE SPLIT FUNCTION)
WHILE #ID2 IS NOT NULL
BEGIN
INSERT #KeyPairs
SELECT #ID,
MAX(CASE WHEN Position = 1 THEN TextValues ELSE '' END),
MAX(CASE WHEN Position = 2 THEN TextValues ELSE '' END)
FROM dbo.Split((SELECT TextField FROM #Output WHERE ID = #ID2), '=')
DELETE #Output
WHERE ID = #ID2
SET #ID2 = (SELECT MIN(ID) FROM #Output)
END
DELETE #WorkList
WHERE ID = #ID
SET #ID = (SELECT MIN(ID) FROM #WorkList)
END
-- WE NOW HAVE A TABLE CONTAINING EAV MODEL STYLE DATA. THIS NEEDS TO BE PIVOTED INTO THE CORRECT FORMAT
-- ENSURE COLUMNS ARE LISTED IN THE ORDER YOU WANT THEM TO APPEAR
SELECT *
FROM #KeyPairs p
PIVOT
( MAX(ValueField)
FOR KeyField IN
( [TimeStamp], [Checksum], [TicketType], [InitialUserType],
[InitialUserID], [CommunicationType], [Date], [Time],
[Service], [Duration], [Cost]
)
) AS PivotTable;
EDIT (4 YEARS LATER)
A recent upvote brought this to my attention and the I hate myself a little bit for ever posting this answer in its current form.
A much better split function would be:
CREATE FUNCTION dbo.Split
(
#List NVARCHAR(MAX),
#Delimiter NVARCHAR(255)
)
RETURNS TABLE
WITH SCHEMABINDING AS
RETURN
( WITH N1 AS (SELECT N FROM (VALUES (1),(1),(1),(1),(1),(1),(1),(1),(1), (1)) n (N)),
N2(N) AS (SELECT 1 FROM N1 a CROSS JOIN N1 b),
N3(N) AS (SELECT 1 FROM N2 a CROSS JOIN N2 b),
N4(N) AS (SELECT 1 FROM N3 a CROSS JOIN N3 b),
cteTally(N) AS
( SELECT 0 UNION ALL
SELECT TOP (DATALENGTH(ISNULL(#List,1))) ROW_NUMBER() OVER (ORDER BY (SELECT NULL))
FROM n4
),
cteStart(N1) AS
( SELECT t.N+1
FROM cteTally t
WHERE (SUBSTRING(#List,t.N,1) = #Delimiter OR t.N = 0)
)
SELECT Item = SUBSTRING(#List, s.N1, ISNULL(NULLIF(CHARINDEX(#Delimiter,#List,s.N1),0)-s.N1,8000)),
Position = s.N1,
ItemNumber = ROW_NUMBER() OVER(ORDER BY s.N1)
FROM cteStart s
);
Then there is no need for looping at all, you just have a proper set based solution by calling the split function twice to get your EAV style data set:
DECLARE #WorkList TABLE (ID INT IDENTITY(1, 1) NOT NULL, TextField VARCHAR(MAX))
INSERT #WorkList
SELECT '08:34:52 Checksum=180957248,TicketType=6,InitialUserType=G,InitialUserID=520,CommunicationType=Incoming,Date=26-03-2012,Time=08:35:00,Service=ST,Duration=00:00:14,Cost=0.12'
UNION
SELECT '08:34:52 Checksum=180957249,TicketType=5,InitialUserType=H,InitialUserID=521,CommunicationType=Outgoing,Date=27-03-2012,Time=14:27:00,Service=ST,Duration=00:15:12,Cost=0.37';
WITH KeyPairs AS
( SELECT w.ID,
[Timestamp] = LEFT(w.TextField, CHARINDEX(' ', w.TextField)),
KeyField = MAX(CASE WHEN v.ItemNumber = 1 THEN v.Item END),
ValueField = MAX(CASE WHEN v.ItemNumber = 2 THEN v.Item END)
FROM #WorkList AS w
CROSS APPLY dbo.Split(SUBSTRING(TextField, CHARINDEX(' ', TextField) + 1, LEN(TextField)), ',') AS kp
CROSS APPLY dbo.Split(kp.Item, '=') AS v
GROUP BY w.ID, kp.ItemNumber,w.TextField
)
SELECT *
FROM KeyPairs AS kp
PIVOT
( MAX(ValueField)
FOR KeyField IN
( [Checksum], [TicketType], [InitialUserType],
[InitialUserID], [CommunicationType], [Date], [Time],
[Service], [Duration], [Cost]
)
) AS pvt;