How to extract multiple strings from single rows in SQL Server

Question

I have e.g. the following table data:

id    |    text
--------------------------------------------------------------------------------
1     |  Peter (Peter@         


        

Answer 1

You can use a cte recursively to strip out the strings.

declare @T table (id int, [text] nvarchar(max))

insert into @T values (1, 'Peter (Peter@peter.de) and Marta (marty@gmail.com) are doing fine.')
insert into @T values (2, 'Nothing special here')
insert into @T values (3, 'Another email address (me@my.com)')

;with cte([text], email)
as
(
    select
        right([text], len([text]) - charindex(')', [text], 0)),
        substring([text], charindex('(', [text], 0) + 1, charindex(')', [text], 0) - charindex('(', [text], 0) - 1) 
    from @T
    where charindex('(', [text], 0) > 0
    union all
    select
        right([text], len([text]) - charindex(')', [text], 0)),
        substring([text], charindex('(', [text], 0) + 1, charindex(')', [text], 0) - charindex('(', [text], 0) - 1) 
    from cte
    where charindex('(', [text], 0) > 0
)
select email
from cte

Result

email
Peter@peter.de
me@my.com
marty@gmail.com

Answer 2

THe substring functions have starting position parameter. So you find the first occurrence,and start the next search (in your loop) at the occurrence position + occurenceLength. You'd need to write a function that returns the values either as a delimited string or table. Use the @-sign to find your way into the email address, and then scan backwards and forwards until you reach white space or a character that's invalid in an email address (or the start-pos or the beginning or the last char).

Answer 3

This assumes there are no rogue parentheses and you would need to add some additional replaces in if your text can contain any XML entity characters.

WITH basedata(id, [text])
     AS (SELECT 1, 'Peter (Peter@peter.de) and Marta (marty@gmail.com) are doing fine.'
         UNION ALL
         SELECT 2, 'Nothing special here'
         UNION ALL
         SELECT 3, 'Another email address (me@my.com)'),
     cte(id, t, x)
     AS (SELECT *,
                CAST('<foo>' + REPLACE(REPLACE([text],'(','<bar>'),')','</bar>') + '</foo>' AS XML)
         FROM   basedata)
SELECT id,
       a.value('.', 'nvarchar(max)') as address
FROM   cte
       CROSS APPLY x.nodes('//foo/bar') as addresses(a)