SQL Split function

Question

I'm looking for a way to do this ...

SELECT FirstName, LastName, Split(AddressBlock, '  ', 1), Split(AddressBlock, ' ', 2), PostCode 
FROM Contacts

The arguments I want to pass are ...

1. The address
2. The separator (current situation requires 2 spaces but this might be a comma or a space followed by a comma) or something else (it varies).
3. The address part I want to return (i don't always need all parts of the split result).

I seem to be able to find a few examples of splitting functions about the internet but they return a table containing the entire set of split parts.

My SQL skills aren't that great so I need the answer to be ultra simple. I'm always working with nvarchar data and the function needs to be reusable.

Answer 1

If you want a user-defined function to do this, this should work. Not that pretty, but...

CREATE FUNCTION dbo.SplitStringPart (
    @input nvarchar(MAX),
    @separator nvarchar(10),
    @index int
) RETURNS nvarchar(MAX)
BEGIN

DECLARE @counter int,
        @position int,
        @oldposition int,
        @separatorlength int,
        @result nvarchar(MAX)

SET @separatorlength = DATALENGTH(@separator) / 2
IF @separatorlength = 0 RETURN NULL

SET @result = NULL

SET @counter = 1
SET @position = -2

WHILE (@counter <= @index)
BEGIN

    SET @oldposition = @position
    SET @position = CHARINDEX(@separator, @input, @position + 1)
    IF @position = 0 AND @counter < @index
    BEGIN
        SET @oldposition = 0
        BREAK
    END
    SET @counter = @counter + 1

END

IF @oldposition = 0 AND @position = 0
    RETURN NULL
ELSE IF @oldposition < 0
BEGIN
    IF @position = 0 AND @index = 1
        SET @result = @input
    ELSE
        SET @result = SUBSTRING(@input, 0, @position)
END
ELSE IF @position <= 0
    SET @result = SUBSTRING(@input, @oldposition + @separatorlength, LEN(@input) - @oldposition - @separatorlength)
ELSE
    SET @result = SUBSTRING(@input, @oldposition + @separatorlength, @position - @oldposition - @separatorlength)

RETURN @result

END
GO

Answer 2

It's not pretty, but add this to you SQL statement and it should work:

CASE 
WHEN charindex(' ', substring(AddressBlock, (charindex(' ', AddressBlock) + 1), len(AddressBlock))) > 0 THEN substring(AddressBlock, (charindex(' ', AddressBlock) + 1), charindex(' ', substring(AddressBlock, (charindex(' ', AddressBlock) + 1), len(AddressBlock))) - 1)
ELSE substring(AddressBlock, (charindex(' ', AddressBlock) + 1), len(AddressBlock))    
END AS 'Address 1', 
CASE WHEN charindex(' ', substring(AddressBlock, (charindex(' ', AddressBlock) + 1), len(AddressBlock))) > 0 THEN substring(AddressBlock, charindex(' ', AddressBlock) + charindex(' ', substring(AddressBlock, (charindex(' ', AddressBlock) + 1), len(AddressBlock))) + 1, Len(AddressBlock))
ELSE ''
END AS 'Address 2'

Answer 3

Here is my version of the answer. This is MUCH faster and robust. No need to fuss around with substrings, charindex, etc.

CREATE FUNCTION [dbo].[SplitArray]
(
    @RowToSplit nvarchar(MAX),
    @Delimeter nvarchar(MAX)
)  
RETURNS @RtnValue table (ID bigint IDENTITY, Data nvarchar(MAX)) 
AS  
BEGIN 
    DECLARE @xml xml
    SET @xml = '<field>' + REPLACE(@RowToSplit, @Delimeter, '</field><field>') + '</field>'
    INSERT INTO @RtnValue(data)
    SELECT  tbl.c.value('.','nvarchar(max)')
    FROM @xml.nodes('/field') tbl(c)
    RETURN
END

You would simply use the resultant split values in a table, like this:

SELECT Data FROM dbo.SplitArray('this is great',' ')

This will return:

Data
============
this
is
great