Turning a Comma Separated string into individual rows - sql-server

Question

I have a SQL Table like this:
| SomeID | OtherID | Data
+----------------+-------------+-------------------
| abcdef-..... | cdef123-... | 18,20,22
| abcdef-..... | 4554a24-... | 17,19
| 987654-..... | 12324a2-... | 13,19,20
is there a query where I can perform a query like SELECT OtherID, SplitData WHERE SomeID = 'abcdef-.......' that returns individual rows, like this:
| OtherID | SplitData
+-------------+-------------------
| cdef123-... | 18
| cdef123-... | 20
| cdef123-... | 22
| 4554a24-... | 17
| 4554a24-... | 19
Basically split my data at the comma into individual rows?
I am aware that storing a comma-separated string into a relational database sounds dumb, but the normal use case in the consumer application makes that really helpful.
I don't want to do the split in the application as I need paging, so I wanted to explore options before refactoring the whole app.
It's SQL Server 2008 (non-R2).

Answer 1

You can use the wonderful recursive functions from SQL Server:
Sample table:
CREATE TABLE Testdata
(
SomeID INT,
OtherID INT,
String VARCHAR(MAX)
);
INSERT Testdata SELECT 1, 9, '18,20,22';
INSERT Testdata SELECT 2, 8, '17,19';
INSERT Testdata SELECT 3, 7, '13,19,20';
INSERT Testdata SELECT 4, 6, '';
INSERT Testdata SELECT 9, 11, '1,2,3,4';
The query
WITH tmp(SomeID, OtherID, DataItem, String) AS
(
SELECT
SomeID,
OtherID,
LEFT(String, CHARINDEX(',', String + ',') - 1),
STUFF(String, 1, CHARINDEX(',', String + ','), '')
FROM Testdata
UNION all
SELECT
SomeID,
OtherID,
LEFT(String, CHARINDEX(',', String + ',') - 1),
STUFF(String, 1, CHARINDEX(',', String + ','), '')
FROM tmp
WHERE
String > ''
)
SELECT
SomeID,
OtherID,
DataItem
FROM tmp
ORDER BY SomeID;
-- OPTION (maxrecursion 0)
-- normally recursion is limited to 100. If you know you have very long
-- strings, uncomment the option
Output
SomeID | OtherID | DataItem
--------+---------+----------
1 | 9 | 18
1 | 9 | 20
1 | 9 | 22
2 | 8 | 17
2 | 8 | 19
3 | 7 | 13
3 | 7 | 19
3 | 7 | 20
4 | 6 |
9 | 11 | 1
9 | 11 | 2
9 | 11 | 3
9 | 11 | 4

Answer 2

Finally, the wait is over with SQL Server 2016. They have introduced the Split string function, STRING_SPLIT:
select OtherID, cs.Value --SplitData
from yourtable
cross apply STRING_SPLIT (Data, ',') cs
All the other methods to split string like XML, Tally table, while loop, etc.. have been blown away by this STRING_SPLIT function.
Here is an excellent article with performance comparison: Performance Surprises and Assumptions: STRING_SPLIT.
For older versions, using tally table here is one split string function(best possible approach)
CREATE FUNCTION [dbo].[DelimitedSplit8K]
(#pString VARCHAR(8000), #pDelimiter CHAR(1))
RETURNS TABLE WITH SCHEMABINDING AS
RETURN
--===== "Inline" CTE Driven "Tally Table" produces values from 0 up to 10,000...
-- enough to cover NVARCHAR(4000)
WITH E1(N) AS (
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
), --10E+1 or 10 rows
E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
cteTally(N) AS (--==== This provides the "base" CTE and limits the number of rows right up front
-- for both a performance gain and prevention of accidental "overruns"
SELECT TOP (ISNULL(DATALENGTH(#pString),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
),
cteStart(N1) AS (--==== This returns N+1 (starting position of each "element" just once for each delimiter)
SELECT 1 UNION ALL
SELECT t.N+1 FROM cteTally t WHERE SUBSTRING(#pString,t.N,1) = #pDelimiter
),
cteLen(N1,L1) AS(--==== Return start and length (for use in substring)
SELECT s.N1,
ISNULL(NULLIF(CHARINDEX(#pDelimiter,#pString,s.N1),0)-s.N1,8000)
FROM cteStart s
)
--===== Do the actual split. The ISNULL/NULLIF combo handles the length for the final element when no delimiter is found.
SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY l.N1),
Item = SUBSTRING(#pString, l.N1, l.L1)
FROM cteLen l
;
Referred from Tally OH! An Improved SQL 8K “CSV Splitter” Function

Answer 3

Check this
SELECT A.OtherID,
Split.a.value('.', 'VARCHAR(100)') AS Data
FROM
(
SELECT OtherID,
CAST ('<M>' + REPLACE(Data, ',', '</M><M>') + '</M>' AS XML) AS Data
FROM Table1
) AS A CROSS APPLY Data.nodes ('/M') AS Split(a);

Answer 4

Very late but try this out:
SELECT ColumnID, Column1, value --Do not change 'value' name. Leave it as it is.
FROM tbl_Sample
CROSS APPLY STRING_SPLIT(Tags, ','); --'Tags' is the name of column containing comma separated values
So we were having this:
tbl_Sample :
ColumnID| Column1 | Tags
--------|-----------|-------------
1 | ABC | 10,11,12
2 | PQR | 20,21,22
After running this query:
ColumnID| Column1 | value
--------|-----------|-----------
1 | ABC | 10
1 | ABC | 11
1 | ABC | 12
2 | PQR | 20
2 | PQR | 21
2 | PQR | 22
Thanks!

Answer 5

select t.OtherID,x.Kod
from testData t
cross apply (select Code from dbo.Split(t.Data,',') ) x

Answer 6

As of Feb 2016 - see the TALLY Table Example - very likely to outperform my TVF below, from Feb 2014. Keeping original post below for posterity:
Too much repeated code for my liking in the above examples. And I dislike the performance of CTEs and XML. Also, an explicit Id so that consumers that are order specific can specify an ORDER BY clause.
CREATE FUNCTION dbo.Split
(
#Line nvarchar(MAX),
#SplitOn nvarchar(5) = ','
)
RETURNS #RtnValue table
(
Id INT NOT NULL IDENTITY(1,1) PRIMARY KEY CLUSTERED,
Data nvarchar(100) NOT NULL
)
AS
BEGIN
IF #Line IS NULL RETURN;
DECLARE #split_on_len INT = LEN(#SplitOn);
DECLARE #start_at INT = 1;
DECLARE #end_at INT;
DECLARE #data_len INT;
WHILE 1=1
BEGIN
SET #end_at = CHARINDEX(#SplitOn,#Line,#start_at);
SET #data_len = CASE #end_at WHEN 0 THEN LEN(#Line) ELSE #end_at-#start_at END;
INSERT INTO #RtnValue (data) VALUES( SUBSTRING(#Line,#start_at,#data_len) );
IF #end_at = 0 BREAK;
SET #start_at = #end_at + #split_on_len;
END;
RETURN;
END;

Answer 7

Nice to see that it have been solved in the 2016 version, but for all of those that is not on that, here are two generalized and simplified versions of the methods above.
The XML-method is shorter, but of course requires the string to allow for the xml-trick (no 'bad' chars.)
XML-Method:
create function dbo.splitString(#input Varchar(max), #Splitter VarChar(99)) returns table as
Return
SELECT Split.a.value('.', 'VARCHAR(max)') AS Data FROM
( SELECT CAST ('<M>' + REPLACE(#input, #Splitter, '</M><M>') + '</M>' AS XML) AS Data
) AS A CROSS APPLY Data.nodes ('/M') AS Split(a);
Recursive method:
create function dbo.splitString(#input Varchar(max), #Splitter Varchar(99)) returns table as
Return
with tmp (DataItem, ix) as
( select #input , CHARINDEX('',#Input) --Recu. start, ignored val to get the types right
union all
select Substring(#input, ix+1,ix2-ix-1), ix2
from (Select *, CHARINDEX(#Splitter,#Input+#Splitter,ix+1) ix2 from tmp) x where ix2<>0
) select DataItem from tmp where ix<>0
Function in action
Create table TEST_X (A int, CSV Varchar(100));
Insert into test_x select 1, 'A,B';
Insert into test_x select 2, 'C,D';
Select A,data from TEST_X x cross apply dbo.splitString(x.CSV,',') Y;
Drop table TEST_X
XML-METHOD 2: Unicode Friendly 😀 (Addition courtesy of Max Hodges)
create function dbo.splitString(#input nVarchar(max), #Splitter nVarchar(99)) returns table as
Return
SELECT Split.a.value('.', 'NVARCHAR(max)') AS Data FROM
( SELECT CAST ('<M>' + REPLACE(#input, #Splitter, '</M><M>') + '</M>' AS XML) AS Data
) AS A CROSS APPLY Data.nodes ('/M') AS Split(a);

Answer 8

Please refer below TSQL. STRING_SPLIT function is available only under compatibility level 130 and above.
TSQL:
DECLARE #stringValue NVARCHAR(400) = 'red,blue,green,yellow,black';
DECLARE #separator CHAR = ',';
SELECT [value] As Colour
FROM STRING_SPLIT(#stringValue, #separator);
RESULT:
Colour
red
blue
green
yellow
black

Answer 9

I know it has a lot of answers, but I want to write my version of split function like others and like string_split SQL Server 2016 native function.
create function [dbo].[Split]
(
#Value nvarchar(max),
#Delimiter nvarchar(50)
)
returns #tbl table
(
Seq int primary key identity(1, 1),
Value nvarchar(max)
)
as begin
declare #Xml xml = cast('<d>' + replace(#Value, #Delimiter, '</d><d>') + '</d>' as xml);
insert into #tbl
(Value)
select a.split.value('.', 'nvarchar(max)') as Value
from #Xml.nodes('/d') a(split);
return;
end;
Seq column is primary key to support fast join with other real table or Split function returned table.
Used XML function to support large data (looping version will slow down significantly when you have large data)
Here's a answer to question.
CREATE TABLE Testdata
(
SomeID INT,
OtherID INT,
String VARCHAR(MAX)
);
INSERT Testdata SELECT 1, 9, '18,20,22';
INSERT Testdata SELECT 2, 8, '17,19';
INSERT Testdata SELECT 3, 7, '13,19,20';
INSERT Testdata SELECT 4, 6, '';
INSERT Testdata SELECT 9, 11, '1,2,3,4';
select t.SomeID, t.OtherID, s.Value
from Testdata t
cross apply dbo.Split(t.String, ',') s;
--Output
SomeID OtherID Value
1 9 18
1 9 20
1 9 22
2 8 17
2 8 19
3 7 13
3 7 19
3 7 20
4 6
9 11 1
9 11 2
9 11 3
9 11 4
Joining Split with other split
declare #Names nvarchar(max) = 'a,b,c,d';
declare #Codes nvarchar(max) = '10,20,30,40';
select n.Seq, n.Value Name, c.Value Code
from dbo.Split(#Names, ',') n
inner join dbo.Split(#Codes, ',') c on n.Seq = c.Seq;
--Output
Seq Name Code
1 a 10
2 b 20
3 c 30
4 d 40
Split two times
declare #NationLocSex nvarchar(max) = 'Korea,Seoul,1;Vietnam,Kiengiang,0;China,Xian,0';
with rows as
(
select Value
from dbo.Split(#NationLocSex, ';')
)
select rw.Value r, cl.Value c
from rows rw
cross apply dbo.Split(rw.Value, ',') cl;
--Output
r c
Korea,Seoul,1 Korea
Korea,Seoul,1 Seoul
Korea,Seoul,1 1
Vietnam,Kiengiang,0 Vietnam
Vietnam,Kiengiang,0 Kiengiang
Vietnam,Kiengiang,0 0
China,Xian,0 China
China,Xian,0 Xian
China,Xian,0 0
Split to columns
declare #Numbers nvarchar(50) = 'First,Second,Third';
with t as
(
select case when Seq = 1 then Value end f1,
case when Seq = 2 then Value end f2,
case when Seq = 3 then Value end f3
from dbo.Split(#Numbers, ',')
)
select min(f1) f1, min(f2) f2, min(f3) f3
from t;
--Output
f1 f2 f3
First Second Third
Generate rows by range
declare #Ranges nvarchar(50) = '1-2,4-6';
declare #Numbers table (Num int);
insert into #Numbers values (1),(2),(3),(4),(5),(6),(7),(8);
with t as
(
select r.Seq, r.Value,
min(case when ft.Seq = 1 then ft.Value end) ValueFrom,
min(case when ft.Seq = 2 then ft.Value end) ValueTo
from dbo.Split(#Ranges, ',') r
cross apply dbo.Split(r.Value, '-') ft
group by r.Seq, r.Value
)
select t.Seq, t.Value, t.ValueFrom, t.ValueTo, n.Num
from t
inner join #Numbers n on n.Num between t.ValueFrom and t.ValueTo;
--Output
Seq Value ValueFrom ValueTo Num
1 1-2 1 2 1
1 1-2 1 2 2
2 4-6 4 6 4
2 4-6 4 6 5
2 4-6 4 6 6

Answer 10

DECLARE #id_list VARCHAR(MAX) = '1234,23,56,576,1231,567,122,87876,57553,1216';
DECLARE #table TABLE ( id VARCHAR(50) );
DECLARE #x INT = 0;
DECLARE #firstcomma INT = 0;
DECLARE #nextcomma INT = 0;
SET #x = LEN(#id_list) - LEN(REPLACE(#id_list, ',', '')) + 1; -- number of ids in id_list
WHILE #x > 0
BEGIN
SET #nextcomma = CASE WHEN CHARINDEX(',', #id_list, #firstcomma + 1) = 0
THEN LEN(#id_list) + 1
ELSE CHARINDEX(',', #id_list, #firstcomma + 1)
END;
INSERT INTO #table
VALUES ( SUBSTRING(#id_list, #firstcomma + 1, (#nextcomma - #firstcomma) - 1) );
SET #firstcomma = CHARINDEX(',', #id_list, #firstcomma + 1);
SET #x = #x - 1;
END;
SELECT *
FROM #table;

Answer 11

;WITH tmp(SomeID, OtherID, DataItem, Data) as (
SELECT SomeID, OtherID, LEFT(Data, CHARINDEX(',',Data+',')-1),
STUFF(Data, 1, CHARINDEX(',',Data+','), '')
FROM Testdata
WHERE Data > ''
)
SELECT SomeID, OtherID, Data
FROM tmp
ORDER BY SomeID
with only tiny little modification to above query...

Answer 12

By creating this function ([DelimitedSplit]) which splits a string, you could do an OUTER APPLY to your SELECT.
CREATE FUNCTION [dbo].[DelimitedSplit]
--===== Define I/O parameters
(#pString VARCHAR(8000), #pDelimiter CHAR(1))
--WARNING!!! DO NOT USE MAX DATA-TYPES HERE! IT WILL KILL PERFORMANCE!
RETURNS TABLE WITH SCHEMABINDING AS
RETURN
--===== "Inline" CTE Driven "Tally Table" produces values from 1 up to 10,000...
-- enough to cover VARCHAR(8000)
WITH E1(N) AS (
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
), --10E+1 or 10 rows
E2(N) AS (SELECT 1 FROM E1 a INNER JOIN E1 b ON b.N = a.N), --10E+2 or 100 rows
E4(N) AS (SELECT 1 FROM E2 a INNER JOIN E2 b ON b.N = a.N), --10E+4 or 10,000 rows max
cteTally(N) AS (--==== This provides the "base" CTE and limits the number of rows right up front
-- for both a performance gain and prevention of accidental "overruns"
SELECT TOP (ISNULL(DATALENGTH(#pString),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
),
cteStart(N1) AS (--==== This returns N+1 (starting position of each "element" just once for each delimiter)
SELECT 1 UNION ALL
SELECT t.N+1 FROM cteTally t WHERE SUBSTRING(#pString,t.N,1) = #pDelimiter
),
cteLen(N1,L1) AS(--==== Return start and length (for use in substring)
SELECT s.N1,
ISNULL(NULLIF(CHARINDEX(#pDelimiter,#pString,s.N1),0)-s.N1,8000)
FROM cteStart s
)
--===== Do the actual split. The ISNULL/NULLIF combo handles the length for the final element when no delimiter is found.
SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY l.N1),
Item = SUBSTRING(#pString, l.N1, l.L1)
FROM cteLen l
;
TEST
CREATE TABLE #Testdata
(
SomeID INT,
OtherID INT,
String VARCHAR(MAX)
);
INSERT #Testdata SELECT 1, 9, '18,20,22';
INSERT #Testdata SELECT 2, 8, '17,19';
INSERT #Testdata SELECT 3, 7, '13,19,20';
INSERT #Testdata SELECT 4, 6, '';
INSERT #Testdata SELECT 9, 11, '1,2,3,4';
SELECT
*
FROM #Testdata
OUTER APPLY [dbo].[DelimitedSplit](String,',');
DROP TABLE #Testdata;
RESULT
SomeID OtherID String ItemNumber Item
1 9 18,20,22 1 18
1 9 18,20,22 2 20
1 9 18,20,22 3 22
2 8 17,19 1 17
2 8 17,19 2 19
3 7 13,19,20 1 13
3 7 13,19,20 2 19
3 7 13,19,20 3 20
4 6 1
9 11 1,2,3,4 1 1
9 11 1,2,3,4 2 2
9 11 1,2,3,4 3 3
9 11 1,2,3,4 4 4

Answer 13

Function
CREATE FUNCTION dbo.SplitToRows (#column varchar(100), #separator varchar(10))
RETURNS #rtnTable TABLE
(
ID int identity(1,1),
ColumnA varchar(max)
)
AS
BEGIN
DECLARE #position int = 0;
DECLARE #endAt int = 0;
DECLARE #tempString varchar(100);
set #column = ltrim(rtrim(#column));
WHILE #position<=len(#column)
BEGIN
set #endAt = CHARINDEX(#separator,#column,#position);
if(#endAt=0)
begin
Insert into #rtnTable(ColumnA) Select substring(#column,#position,len(#column)-#position);
break;
end;
set #tempString = substring(ltrim(rtrim(#column)),#position,#endAt-#position);
Insert into #rtnTable(ColumnA) select #tempString;
set #position=#endAt+1;
END;
return;
END;
Use case
select * from dbo.SplitToRows('T14; p226.0001; eee; 3554;', ';');
Or just a select with multiple result set
DECLARE #column varchar(max)= '1234; 4748;abcde; 324432';
DECLARE #separator varchar(10) = ';';
DECLARE #position int = 0;
DECLARE #endAt int = 0;
DECLARE #tempString varchar(100);
set #column = ltrim(rtrim(#column));
WHILE #position<=len(#column)
BEGIN
set #endAt = CHARINDEX(#separator,#column,#position);
if(#endAt=0)
begin
Select substring(#column,#position,len(#column)-#position);
break;
end;
set #tempString = substring(ltrim(rtrim(#column)),#position,#endAt-#position);
select #tempString;
set #position=#endAt+1;
END;

Answer 14

When using this approach you have to make sure that none of your values contains something that would be illegal XML – user1151923
I always use the XML method. Make sure you use VALID XML. I have two functions to convert between valid XML and Text. (I tend to strip out the carriage returns as I don't usually need them.
CREATE FUNCTION dbo.udf_ConvertTextToXML (#Text varchar(MAX))
RETURNS varchar(MAX)
AS
BEGIN
SET #Text = REPLACE(#Text,CHAR(10),'');
SET #Text = REPLACE(#Text,CHAR(13),'');
SET #Text = REPLACE(#Text,'<','<');
SET #Text = REPLACE(#Text,'&','&');
SET #Text = REPLACE(#Text,'>','>');
SET #Text = REPLACE(#Text,'''','&apos;');
SET #Text = REPLACE(#Text,'"','"');
RETURN #Text;
END;
CREATE FUNCTION dbo.udf_ConvertTextFromXML (#Text VARCHAR(MAX))
RETURNS VARCHAR(max)
AS
BEGIN
SET #Text = REPLACE(#Text,'<','<');
SET #Text = REPLACE(#Text,'&','&');
SET #Text = REPLACE(#Text,'>','>');
SET #Text = REPLACE(#Text,'&apos;','''');
SET #Text = REPLACE(#Text,'"','"');
RETURN #Text;
END;

Answer 15

Below works on sql server 2008
select *, ROW_NUMBER() OVER(order by items) as row#
from
( select 134 myColumn1, 34 myColumn2, 'd,c,k,e,f,g,h,a' comaSeperatedColumn) myTable
cross apply
SPLIT (rtrim(comaSeperatedColumn), ',') splitedTable -- gives 'items' column
Will get all Cartesian product with the origin table columns plus "items" of split table.

Answer 16

You can use the following function to extract data
CREATE FUNCTION [dbo].[SplitString]
(
#RowData NVARCHAR(MAX),
#Delimeter NVARCHAR(MAX)
)
RETURNS #RtnValue TABLE
(
ID INT IDENTITY(1,1),
Data NVARCHAR(MAX)
)
AS
BEGIN
DECLARE #Iterator INT;
SET #Iterator = 1;
DECLARE #FoundIndex INT;
SET #FoundIndex = CHARINDEX(#Delimeter,#RowData);
WHILE (#FoundIndex>0)
BEGIN
INSERT INTO #RtnValue (data)
SELECT
Data = LTRIM(RTRIM(SUBSTRING(#RowData, 1, #FoundIndex - 1)));
SET #RowData = SUBSTRING(#RowData,
#FoundIndex + DATALENGTH(#Delimeter) / 2,
LEN(#RowData));
SET #Iterator = #Iterator + 1;
SET #FoundIndex = CHARINDEX(#Delimeter, #RowData);
END;
INSERT INTO #RtnValue (Data)
SELECT Data = LTRIM(RTRIM(#RowData));
RETURN;
END;