T-SQL split string based on delimiter

Question

I have some data that I would like to split based on a delimiter that may or may not exist.

Example data:

John/Smith
Jane/Doe
Steve
Bob/Johnson

I am using the following code to split this data into First and Last names:

SELECT SUBSTRING(myColumn, 1, CHARINDEX('/', myColumn)-1) AS FirstName,
       SUBSTRING(myColumn, CHARINDEX('/', myColumn) + 1, 1000) AS LastName
FROM   MyTable

The results I would like:

FirstName---LastName
John--------Smith
Jane--------Doe
Steve-------NULL
Bob---------Johnson

This code works just fine as long as all the rows have the anticipated delimiter, but errors out when a row does not:

"Invalid length parameter passed to the LEFT or SUBSTRING function."

How can I re-write this to work properly?

Solution 1

May be this will help you.

SELECT SUBSTRING(myColumn, 1, CASE CHARINDEX('/', myColumn)
            WHEN 0
                THEN LEN(myColumn)
            ELSE CHARINDEX('/', myColumn) - 1
            END) AS FirstName
    ,SUBSTRING(myColumn, CASE CHARINDEX('/', myColumn)
            WHEN 0
                THEN LEN(myColumn) + 1
            ELSE CHARINDEX('/', myColumn) + 1
            END, 1000) AS LastName
FROM MyTable

Solution 2

For those looking for answers for SQL Server 2016+. Use the built-in STRING_SPLIT function

Eg:

DECLARE @tags NVARCHAR(400) = 'clothing,road,,touring,bike'  

SELECT value  
FROM STRING_SPLIT(@tags, ',')  
WHERE RTRIM(value) <> '';  

Reference: https://msdn.microsoft.com/en-nz/library/mt684588.aspx

Solution 3

SELECT CASE 
        WHEN CHARINDEX('/', myColumn, 0) = 0
            THEN myColumn
        ELSE LEFT(myColumn, CHARINDEX('/', myColumn, 0)-1)
        END AS FirstName
    ,CASE 
        WHEN CHARINDEX('/', myColumn, 0) = 0
            THEN ''
        ELSE RIGHT(myColumn, CHARINDEX('/', REVERSE(myColumn), 0)-1)
        END AS LastName
FROM MyTable

Solution 4

Try filtering out the rows that contain strings with the delimiter and work on those only like:

SELECT SUBSTRING(myColumn, 1, CHARINDEX('/', myColumn)-1) AS FirstName,
       SUBSTRING(myColumn, CHARINDEX('/', myColumn) + 1, 1000) AS LastName
FROM   MyTable
WHERE CHARINDEX('/', myColumn) > 0

Or

SELECT SUBSTRING(myColumn, 1, CHARINDEX('/', myColumn)-1) AS FirstName,
       SUBSTRING(myColumn, CHARINDEX('/', myColumn) + 1, 1000) AS LastName
FROM   MyTable
WHERE myColumn LIKE '%/%'

Solution 5

ALTER FUNCTION [dbo].[split_string](
          @delimited NVARCHAR(MAX),
          @delimiter NVARCHAR(100)
        ) RETURNS @t TABLE (id INT IDENTITY(1,1), val NVARCHAR(MAX))
AS
BEGIN
  DECLARE @xml XML
  SET @xml = N'<t>' + REPLACE(@delimited,@delimiter,'</t><t>') + '</t>'

  INSERT INTO @t(val)
  SELECT  r.value('.','varchar(MAX)') as item
  FROM  @xml.nodes('/t') as records(r)
  RETURN
END

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Comments

[ripvlan]

I'm not sure this answers the question nor is it as useful as the CASE statement methods above. The STRING_SPLIT function turns it into a Table that is joined. So how does one get the first-position "First name" the second "Last Name" ? Using Cross-Apply transformed my ds into multiple rows. It's a great way transform String data into a table. Like the OP, I'm trying to transform a single column into two columns. STRING_SPLIT turns it into two rows and no way to tell which row is the "first" "second" "third" (unless Over works). But that becomes more complicated.