Extract email address from string using tsql

Question

I\'m trying to extract email addresses from an existing comments field and put it into its own column. The string may be something like this \"this is an example comment wit

Answer 1

Stephan's answer is great when looking for a single email address in each row.

However, I was running into this error when trying to get multiple email addresses in each row:

Invalid length parameter passed to the LEFT or SUBSTRING function

I used this answer from DBA Stack Exchange to get all of the positions of @ inside the string. It entails a table-valued function that returns the number of positions equal to the number a certain pattern inside the string. I also had to modify the CROSS APPLY functions to handle multiple email addresses as well.

My Table:

DECLARE @Table TABLE (comment VARCHAR(500));
INSERT INTO @Table (comment)
VALUES ('blah blah My.EmailAddress@domain.org more blah someemailaddress@domain.com even more blah asdf@gmail.com'),
       ('blah hello.world@domain.org more'),
       ('no email')

Table-valued Function:

CREATE FUNCTION dbo.fnFindPatternLocation
(
    @string NVARCHAR(MAX),
    @term   NVARCHAR(255)
)
RETURNS TABLE
AS
    RETURN 
    (
        SELECT pos = Number - LEN(@term) 
        FROM (SELECT Number, Item = LTRIM(RTRIM(SUBSTRING(@string, Number, 
        CHARINDEX(@term, @string + @term, Number) - Number)))
        FROM (SELECT ROW_NUMBER() OVER (ORDER BY [object_id])
        FROM sys.all_objects) AS n(Number)
        WHERE Number > 1 AND Number <= CONVERT(INT, LEN(@string))
        AND SUBSTRING(@term + @string, Number, LEN(@term)) = @term
    ) AS y);
GO

Query:

SELECT comment, pos, SUBSTRING(comment,beginningOfEmail,endOfEmail-beginningOfEmail) AS email
FROM @Table
CROSS APPLY (SELECT pos FROM dbo.fnFindPatternLocation(comment, '@')) AS A(pos)
CROSS APPLY (SELECT CHARINDEX(' ',comment + ' ', pos)) AS B(endOfEmail)
CROSS APPLY (SELECT pos - CHARINDEX(' ', REVERSE(SUBSTRING(comment, 1, pos))) + 2) AS C(beginningOfEmail)

Results:

comment
---------------------------------------------------------------------------------------------------------
blah blah My.EmailAddress@domain.org more blah someemailaddress@domain.com even more blah asdf@gmail.com
blah blah My.EmailAddress@domain.org more blah someemailaddress@domain.com even more blah asdf@gmail.com
blah blah My.EmailAddress@domain.org more blah someemailaddress@domain.com even more blah asdf@gmail.com
blah hello.world@domain.org more

---

pos    email
---    ------------------------------
26     My.EmailAddress@domain.org
64     someemailaddress@domain.com
95     asdf@gmail.com
17     hello.world@domain.org