Using T-SQL, return nth delimited element from a string

Question

I have a need to create a function the will return nth element of a delimited string.

For a data migration project, I am converting JSON audit records stored in a SQL Server database into a structured report using SQL script. Goal is to deliver a sql script and a sql function used by the script without any code.

(This is a short-term fix will be used while a new auditing feature is added the ASP.NET/MVC application)

There is no shortage of delimited string to table examples available. I've chosen a Common Table Expression example http://www.sqlperformance.com/2012/07/t-sql-queries/split-strings

Example: I want to return 67 from '1,222,2,67,888,1111'

Answer 1

This is the easiest answer to retrieve the 67 (type-safe!!):

SELECT CAST('<x>' + REPLACE('1,222,2,67,888,1111',',','</x><x>') + '</x>' AS XML).value('/x[4]','int')

In the following you will find examples how to use this with variables for the string, the delimiter and the position (even for edge-cases with XML-forbidden characters)

##The easy one

This question is not about a string split approach, but about how to get the nth element. The easiest, fully inlineable way would be this IMO:

This is a real one-liner to get part 2 delimited by a space:

DECLARE @input NVARCHAR(100)=N'part1 part2 part3';
SELECT CAST(N'<x>' + REPLACE(@input,N' ',N'</x><x>') + N'</x>' AS XML).value('/x[2]','nvarchar(max)')

##Variables can be used with sql:variable() or sql:column()

Of course you can use variables for delimiter and position (use sql:column to retrieve the position directly from a query's value):

DECLARE @dlmt NVARCHAR(10)=N' ';
DECLARE @pos INT = 2;
SELECT CAST(N'<x>' + REPLACE(@input,@dlmt,N'</x><x>') + N'</x>' AS XML).value('/x[sql:variable("@pos")][1]','nvarchar(max)')

##Edge-Case with XML-forbidden characters

If your string might include forbidden characters, you still can do it this way. Just use FOR XML PATH on your string first to replace all forbidden characters with the fitting escape sequence implicitly.

It's a very special case if - additionally - your delimiter is the semicolon. In this case I replace the delimiter first to '#DLMT#', and replace this to the XML tags finally:

SET @input=N'Some <, > and &;Other äöü@€;One more';
SET @dlmt=N';';
SELECT CAST(N'<x>' + REPLACE((SELECT REPLACE(@input,@dlmt,'#DLMT#') AS [*] FOR XML PATH('')),N'#DLMT#',N'</x><x>') + N'</x>' AS XML).value('/x[sql:variable("@pos")][1]','nvarchar(max)');

##UPDATE for SQL-Server 2016+

Regretfully the developers forgot to return the part's index with STRING_SPLIT. But, using SQL-Server 2016+, there is JSON_VALUE and OPENJSON.

With JSON_VALUE we can pass in the position as the index' array.

For OPENJSON the documentation states clearly:

When OPENJSON parses a JSON array, the function returns the indexes of the elements in the JSON text as keys.

A string like 1,2,3 needs nothing more than brackets: [1,2,3].
A string of words like this is an example needs to be ["this","is","an"," example"].
These are very easy string operations. Just try it out:

DECLARE @str VARCHAR(100)='Hello John Smith';
DECLARE @position INT = 2;

--We can build the json-path '$[1]' using CONCAT
SELECT JSON_VALUE('["' + REPLACE(@str,' ','","') + '"]',CONCAT('$[',@position-1,']'));

--See this for a position safe string-splitter (zero-based):

SELECT  JsonArray.[key] AS [Position]
       ,JsonArray.[value] AS [Part]
FROM OPENJSON('["' + REPLACE(@str,' ','","') + '"]') JsonArray

In this post I tested various approaches and found, that OPENJSON is really fast. Even much faster than the famous "delimitedSplit8k()" method...

##UPDATE 2 - Get the values type-safe

We can use an array within an array simply by using doubled [[]]. This allows for a typed WITH-clause:

DECLARE  @SomeDelimitedString VARCHAR(100)='part1|1|20190920';

DECLARE @JsonArray NVARCHAR(MAX)=CONCAT('[["',REPLACE(@SomeDelimitedString,'|','","'),'"]]');

SELECT @SomeDelimitedString          AS TheOriginal
      ,@JsonArray                    AS TransformedToJSON
      ,ValuesFromTheArray.*
FROM OPENJSON(@JsonArray)
WITH(TheFirstFragment VARCHAR(100) '$[0]'
    ,TheSecondFragment INT '$[1]'
    ,TheThirdFragment DATE '$[2]') ValuesFromTheArray

Answer 2

On Azure SQL Database, and on SQL Server 2022, STRING_SPLIT now has an optional ordinal parameter. If the parameter is omitted, or 0 is passed, then the function acts as it did before, and just returns a value column and the order is not guaranteed. If you pass the parameter with the value 1 then the function returns 2 columns, value, and ordinal which (unsurprisingly) provides the ordinal position of the value within the string.

So, if you wanted the 4th delimited value from the string '1,222,2,67,888,1111' you could do the following:

SELECT [value]
FROM STRING_SPLIT('1,222,2,67,888,1111',',',1)
WHERE ordinal = 4;

If the value was in a column, it would look like this:

SELECT SS.[value]
FROM dbo.YourTable YT
     CROSS APPLY STRING_SPLIT(YT.YourColumn,',',1) SS
WHERE SS.ordinal = 4;

Answer 3

Here is my initial solution... It is based on work by Aaron Bertrand http://www.sqlperformance.com/2012/07/t-sql-queries/split-strings

I simply changed the return type to make it a scalar function.

Example: SELECT dbo.GetSplitString_CTE('1,222,2,67,888,1111',',',4)

CREATE FUNCTION dbo.GetSplitString_CTE
(
   @List       VARCHAR(MAX),
   @Delimiter  VARCHAR(255),
   @ElementNumber int
)
RETURNS VARCHAR(4000)
AS
BEGIN

   DECLARE @result varchar(4000)    
   DECLARE @Items TABLE ( position int IDENTITY PRIMARY KEY,
                          Item VARCHAR(4000)
                         )  

   DECLARE @ll INT = LEN(@List) + 1, @ld INT = LEN(@Delimiter);  

   WITH a AS
   (
       SELECT
           [start] = 1,
           [end]   = COALESCE(NULLIF(CHARINDEX(@Delimiter, 
                       @List, @ld), 0), @ll),
           [value] = SUBSTRING(@List, 1, 
                     COALESCE(NULLIF(CHARINDEX(@Delimiter, 
                       @List, @ld), 0), @ll) - 1)
       UNION ALL
       SELECT
           [start] = CONVERT(INT, [end]) + @ld,
           [end]   = COALESCE(NULLIF(CHARINDEX(@Delimiter, 
                       @List, [end] + @ld), 0), @ll),
           [value] = SUBSTRING(@List, [end] + @ld, 
                     COALESCE(NULLIF(CHARINDEX(@Delimiter, 
                       @List, [end] + @ld), 0), @ll)-[end]-@ld)
       FROM a
       WHERE [end] < @ll
   )
   INSERT @Items SELECT [value]
   FROM a
   WHERE LEN([value]) > 0
   OPTION (MAXRECURSION 0);

   SELECT @result=Item
   FROM @Items
   WHERE position=@ElementNumber

   RETURN @result;
END
GO

Answer 4

How about:

CREATE FUNCTION dbo.NTH_ELEMENT (@Input NVARCHAR(MAX), @Delim CHAR = '-', @N INT = 0)
RETURNS NVARCHAR(MAX)
AS
BEGIN
RETURN (SELECT VALUE FROM STRING_SPLIT(@Input, @Delim) ORDER BY (SELECT NULL) OFFSET @N ROWS FETCH NEXT 1 ROW ONLY)
END

Answer 5

@a - the value (f.e. 'a/bb/ccc/dddd/ee/ff/....')

@p - the desired position (1,2,3...)

@d - the delimeter ( '/' )

trim(substring(replace(@a,@d,replicate(' ',len(@a))),(@p-1)*len(@a)+1,len(@a)))

only problem is - if desired part has trailing or leading blanks they get trimmed.

Completely Based on article from https://exceljet.net/formula/split-text-with-delimiter

Answer 6

In a rare moment of lunacy I just thought that split is far easier if we use XML to parse it out for us:

(Using the variables from @Gary Kindel's answer)

declare @xml xml
set @xml = '<split><el>' + replace(@list,@Delimiter,'</el><el>') + '</el></split>'

select
    el = split.el.value('.','varchar(max)')
from  @xml.nodes('/split/el') split(el))

This lists all elements of the string, split by the specified character.

We can use an xpath test to filter out empty values, and a further xpath test to restrict this to the element we're interested in. In full Gary's function becomes:

alter FUNCTION dbo.GetSplitString_CTE
(
   @List       VARCHAR(MAX),
   @Delimiter  VARCHAR(255),
   @ElementNumber int
)
RETURNS VARCHAR(max)
AS
BEGIN
       -- escape any XML https://dba.stackexchange.com/a/143140/65992  
       set @list = convert(VARCHAR(MAX),(select @list for xml path(''), type));

       declare @xml xml
       set @xml = '<split><el>' + replace(@list,@Delimiter,'</el><el>') + '</el></split>'

       declare @ret varchar(max)
       set @ret = (select
              el = split.el.value('.','varchar(max)')
       from  @xml.nodes('/split/el[string-length(.)>0][position() = sql:variable("@elementnumber")]') split(el))

       return @ret

END

Answer 7

you can put this select into UFN. if you need you can customize it for specifying delimiter as well. in that case your ufn will have two input. number Nth and delimiter to use.

    DECLARE @tlist varchar(max)='10,20,30,40,50,60,70,80,90,100'
    DECLARE @i INT=1, @nth INT=3
    While len(@tlist) <> 0
    BEGIN
            IF @i=@nth
            BEGIN
              select Case when charindex(',',@tlist) <> 0 Then LEFT(@tlist,charindex(',',@tlist)-1)
                          Else @tlist
                    END
            END

              Select @tlist = Case when charindex(',',@tlist) <> 0 Then substring(@tlist,charindex(',',@tlist)+1,len(@tlist))
                          Else ''
                          END

            SELECT @i=@i+1
    END

Answer 8

Alternatively, one can use xml, nodes() and ROW_NUMBER. We can order the elements based on their document order. For example:

DECLARE @Input VARCHAR(100) = '1a,2b,3c,4d,5e,6f,7g,8h'
       ,@Number TINYINT = 3

DECLARE @XML XML;
DECLARE @value VARCHAR(100);

SET @XML = CAST('<x>' + REPLACE(@Input,',','</x><x>') + '</x>' AS XML);

WITH DataSource ([rowID], [rowValue]) AS
(
    SELECT ROW_NUMBER() OVER (ORDER BY T.c ASC) 
            ,T.c.value('.', 'VARCHAR(100)')
    FROM @XML.nodes('./x') T(c)
)
SELECT @value = [rowValue]
FROM DataSource
WHERE [rowID] = @Number;

SELECT @value;

Answer 9

I would rather create a temp table with an identity column and fill it up with output from the SPLIT function.

  CREATE TABLE #tblVals(Id INT IDENTITY(1,1), Val NVARCHAR(100))
  INSERT INTO #tblVals (Val)
  SELECT [value] FROM STRING_SPLIT('Val1-Val3-Val2-Val5', '-')
  SELECT * FROM #tblVals

Now you can easily do something like below.

DECLARE @val2 NVARCHAR(100) = (SELECT TOP 1 Val FROM #tblVals WHERE Id = 2)

See the snapshot below:

Answer 10

We have the answer over below url.

DECLARE @ AS VARCHAR(MAX) = 'Pawan1,Pawan2,Pawan4,Pawan3' 
SELECT VALUE FROM 
(
    SELECT VALUE , ROW_NUMBER() OVER (ORDER BY (SELECT null)) rnk FROM STRING_SPLIT(@, ',')
)x where rnk = 3
GO

https://msbiskills.com/2018/06/15/sql-puzzle-multiple-ways-to-split-a-string-and-get-nth-row-xml-advanced-sql/

Answer 11

You can use STRING_SPLIT with ROW_NUMBER:

SELECT value, idx FROM
(
  SELECT
    value,
    ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) idx
  FROM STRING_SPLIT('Lorem ipsum dolor sit amet.', ' ')
) t
WHERE idx=2

returns second element (idx=2): 'ipsum'

Answer 12

you can create simple table variable and use it as below

Declare @tbl_split Table (Id INT IDENTITY(1,1), VAL VARCHAR(50))
INSERT @tbl_split SELECT VALUE
FROM string_split('999999:01', ':')

Select val from @tbl_split
WHERE Id=2

Answer 13

I don't have enough reputation to comment, so I am adding an answer. Please adjust as appropriate.

I have a problem with Gary Kindel's answer for cases where there is nothing between the two delimiters

If you do select * from dbo.GetSplitString_CTE('abc^def^^ghi','^',3) you get ghi instead of an empty string

If you comment out the WHERE LEN([value]) > 0 line, you get the desired result

Answer 14

I cannot comment on Gary's solution because of my low reputation

I know Gary was referencing another link.

I have struggled to understand why we need this variable

@ld INT = LEN(@Delimiter)

I also don't understand why charindex has to start at the position of length of delimiter, @ld

I tested with many examples with a single character delimiter, and they work. Most of the time, delimiter character is a single character. However, since the developer included the ld as length of delimiter, the code has to work for delimiters that have more than one character

In this case, the following case will fail

11,,,22,,,33,,,44,,,55,,,

I cloned from the codes from this link. http://codebetter.com/raymondlewallen/2005/10/26/quick-t-sql-to-parse-a-delimited-string/

I have tested various scenarios including the delimiters that have more than one character

alter FUNCTION [dbo].[split1]
(
    @string1 VARCHAR(8000) -- List of delimited items
    , @Delimiter VARCHAR(40) = ',' -- delimiter that separates items
    , @ElementNumber int
)
RETURNS varchar(8000)
AS
BEGIN
    declare @position int
    declare @piece varchar(8000)=''
    declare @returnVal varchar(8000)=''
    declare @Pattern varchar(50) = '%' + @Delimiter + '%'
    declare @counter int =0
    declare @ld int = len(@Delimiter)
    declare @ls1 int = len (@string1)
    declare @foundit int = 0

    if patindex(@Pattern , @string1) = 0
        return  ''

    if right(rtrim(@string1),1) <> @Delimiter
        set @string1 = @string1  + @Delimiter

    set @position =  patindex(@Pattern , @string1) + @ld  -1  
    while @position > 0
    begin
        set @counter = @counter +1 
        set @ls1  = len (@string1)
        if (@ls1 >= @ld)
            set @piece = left(@string1, @position - @ld)
        else
            break
        if (@counter = @ElementNumber)
        begin
            set @foundit = 1
                break
        end
        if len(@string1) > 0
        begin
            set @string1 = stuff(@string1, 1, @position, '')
            set @position =  patindex(@Pattern , @string1) + @ld  -1  
        end
        else
        set @position = -1
    end 


    if @foundit =1
        set @returnVal = @piece
    else 
        set @returnVal =  ''
    return @returnVal