SQL - Query Phonenumber that are stored inconsistently

Question

we a phonenumber field in our database and I would like to do a simple lookup query like:

SELECT * FROM TABLE WHERE Phonenumber = \'555123456\'

Answer 1

In Oracle:

SELECT  *
FROM    mytable
WHERE   REGEXP_REPLACE(Phonenumber, '[^0-9]', '') = '5551234567'

In SQL Server 2005+:

WITH    digits AS
        (
        SELECT  1 AS digit
        UNION ALL
        SELECT  digit + 1
        FROM    digits
        WHERE   digit <= 100
        )
SELECT  *
FROM    mytable
WHERE   (
        SELECT  SUBSTRING(number, digit, 1) AS [text()]
        FROM    digits
        WHERE   SUBSTRING(number, digit, 1) BETWEEN '0' AND '9'
        FOR XML PATH('')
        ) = '5551234567'

, or, if you want to see the normalized phone value,

WITH    digits AS
        (
        SELECT  1 AS digit
        UNION ALL
        SELECT  digit + 1
        FROM    digits
        WHERE   digit <= 100
        ),
        phones AS
        (
        SELECT  m.*,
                (
                SELECT  SUBSTRING(number, digit, 1) AS [text()]
                FROM    digits
                WHERE   SUBSTRING(number, digit, 1) BETWEEN '0' AND '9'
                FOR XML PATH('')
                ) AS nphone
        FROM    mytable m
        )
SELECT  *
FROM    phones
WHERE   nphone = '5551234567'

However, you better create another column for normalized phone values, fill it in a trigger and index it, so you can query more efficiently.