Split column value using delimiter and insert into different table - sql-server

Question

I have one table with only one column. That one column contains strings with comma-delimited values. I am trying to select each string from the table > split the string by the comma's > and then insert the results into a different table.
My first table look like this:
DataString
abc,def,gh,i,jkl
mnop,qr,stu,v,wxyz
I would like the data to look like this:
Value1 Value2 Value3 Value4 Value5
abc def gh i jkl
mnop qr stu v wxyz
This is the code I have so far:
DECLARE #valueList varchar(100)
DECLARE #pos INT
DECLARE #len INT
DECLARE #value varchar(100)
Select #valueList = DataString from [dbo].[rawdata]
set #pos = 0
set #len = 0
WHILE CHARINDEX(',', #valueList, #pos+1)>0
BEGIN
set #len = CHARINDEX(',', #valueList, #pos+1) - #pos
set #value = SUBSTRING(#valueList, #pos, #len)
insert into [dbo].[tempTable] (Value1) Values (#value)
set #pos = CHARINDEX(',', #valueList, #pos+#len) +1
END
I am having two problems with this code.
Problem 1:
- my select statement to pull in the column DataString into the variable #valueList is only pulling the last row in the table instead of selecting all of them.
Problem 2:
- my insert into statement can only insert the values as new rows into the table. I cant figure out how to enter the values into their corresponding columns.
Any help on how to fix either of my problems would be greatly appreciated.

Answer 1

So your first issue is that assigning a variable to a column like that in a table is only going to pull one row from that column in table. If you want to loop through each row in a column like you're currently doing, you would need to use a CURSOR or some variant like that to go through each row.
The second issue you have is that your while statement is incorrect. You're missing the last value from it because you stop when there are no more commas in your datastring. There are no more commas at the last value, so it skips the last value. There's a way around this using your current method, but I would recommend an alternative method of splitting your string.
DECLARE #myTable TABLE (datastring VARCHAR(4000));
INSERT #myTable(datastring)
VALUES ('abc,def,gh,i,jkl'),('mnop,qr,stu,v,wxyz');
DECLARE #valueList VARCHAR(4000) = '', #i INT = 1, #pos INT = 0, #len INT = 0, #value VARCHAR(100) = '';
IF OBJECT_ID('tempTable', 'U') IS NOT NULL DROP TABLE tempTable;
CREATE TABLE tempTable (OriginalDataString VARCHAR(4000), stringVal VARCHAR(255), valNum INT);
DECLARE curs CURSOR FOR
SELECT datastring
FROM #myTable;
OPEN curs;
FETCH NEXT FROM curs INTO #valueList;
WHILE ##FETCH_STATUS = 0 BEGIN
SELECT #pos = 0, #len = 0, #i = 1;
WHILE 1 = 1
BEGIN
SET #len = ISNULL(NULLIF(CHARINDEX(',', #valueList, #pos+1), 0) - #pos, LEN(#valueList));
SET #value = SUBSTRING(#valueList, #pos, #len);
INSERT tempTable(OriginalDataString, stringVal, valNum)
VALUES (#valueList, #value, #i);
IF CHARINDEX(',', #valueList, #pos+1) = 0
BREAK;
SET #pos = CHARINDEX(',', #valueList, #pos+#len) + 1;
SET #i += 1;
END
FETCH NEXT FROM curs INTO #valueList;
END
CLOSE curs;
DEALLOCATE curs;
SELECT MAX(CASE WHEN valNum = 1 THEN stringVal END) val1
, MAX(CASE WHEN valNum = 2 THEN stringVal END) val2
, MAX(CASE WHEN valNum = 3 THEN stringVal END) val3
, MAX(CASE WHEN valNum = 4 THEN stringVal END) val4
, MAX(CASE WHEN valNum = 5 THEN stringVal END) val5
FROM tempTable
GROUP BY OriginalDataString;
This uses a cursor to get each datastring in your table, puts each value in a cursor, loops through them to get the value (the loop breaks when you reach the end of the string) and then selects val1, val2, val3, val4, val5 from the resulting table.
But, rather than using a cursor and a while loop, I would recommend the much simpler use of a recursive CTE (or even better, a split function you already have built in).
For example,
DECLARE #myTable TABLE (datastring VARCHAR(4000));
INSERT #myTable(datastring)
VALUES ('abc,def,gh,i,jkl'),('mnop,qr,stu,v,wxyz');
WITH CTE AS (
SELECT datastring
, SUBSTRING(datastring, 1, ISNULL(NULLIF(CHARINDEX(',', datastring), 0) - 1, LEN(datastring))) sString
, NULLIF(CHARINDEX(',', datastring), 0) cIndex
, 1 Lvl
FROM #myTable T
UNION ALL
SELECT datastring
, SUBSTRING(datastring, cIndex + 1, ISNULL(NULLIF(CHARINDEX(',', datastring, cIndex + 1), 0) - 1 - cIndex, LEN(datastring)))
, NULLIF(CHARINDEX(',', datastring, cIndex + 1), 0)
, Lvl + 1
FROM CTE
WHERE cIndex IS NOT NULL)
SELECT MAX(CASE WHEN Lvl = 1 THEN sString END) val1
, MAX(CASE WHEN Lvl = 2 THEN sString END) val2
, MAX(CASE WHEN Lvl = 3 THEN sString END) val3
, MAX(CASE WHEN Lvl = 4 THEN sString END) val4
, MAX(CASE WHEN Lvl = 5 THEN sString END) val5
--, datastring OriginalDataString
FROM CTE
GROUP BY datastring;

Answer 2

Declare #YourTable table (DataString varchar(250))
Insert Into #YourTable values
('abc,def,gh,i,jkl'),
('mnop,qr,stu,v,wxyz')
Select A.*
,Value1=B.Pos1
,Value2=B.Pos2
,Value3=B.Pos3
,Value4=B.Pos4
,Value5=B.Pos5
From #YourTable A
Cross Apply (Select * from [dbo].[udf-Str-Parse-Row](A.DataString,',')) B
Returns
DataString Value1 Value2 Value3 Value4 Value5
abc,def,gh,i,jkl abc def gh i jkl
mnop,qr,stu,v,wxyz mnop qr stu v wxyz
Then UDF if needed
CREATE FUNCTION [dbo].[udf-Str-Parse-Row] (#String varchar(max),#Delimeter varchar(10))
--Usage: Select * from [dbo].[udf-Str-Parse-Row]('Dog,Cat,House,Car',',')
-- Select * from [dbo].[udf-Str-Parse-Row]('John Cappelletti',' ')
-- Select * from [dbo].[udf-Str-Parse-Row]('id26,id46|id658,id967','|')
Returns Table
As
Return (
SELECT Pos1 = xDim.value('/x[1]','varchar(250)')
,Pos2 = xDim.value('/x[2]','varchar(250)')
,Pos3 = xDim.value('/x[3]','varchar(250)')
,Pos4 = xDim.value('/x[4]','varchar(250)')
,Pos5 = xDim.value('/x[5]','varchar(250)')
,Pos6 = xDim.value('/x[6]','varchar(250)')
,Pos7 = xDim.value('/x[7]','varchar(250)')
,Pos8 = xDim.value('/x[8]','varchar(250)')
,Pos9 = xDim.value('/x[9]','varchar(250)')
FROM (Select Cast('<x>' + Replace(#String,#Delimeter,'</x><x>')+'</x>' as XML) as xDim) A
)