Find rows with duplicate/similar column values MySQL

Question

I want to select from the following table all the rows which have similar values in the fname column as the first in their order. IOW from this table I want to retrieve rows

Answer 1

I've re-read your initial question and I've came up with the following solution:

SELECT *
FROM   users
WHERE  id IN
       (SELECT id
       FROM    users t4
               INNER JOIN
                       (SELECT  soundex(fname) AS snd,
                                COUNT(*)       AS cnt
                       FROM     users          AS t5
                       GROUP BY snd
                       HAVING   cnt > 1
                       )
                       AS t6
               ON      soundex(t4.fname)=snd
       )
AND    id NOT IN
       (SELECT  MIN(t2.id) AS wanted
       FROM     users t2
                INNER JOIN
                         (SELECT  soundex(fname) AS snd,
                                  COUNT(*)       AS cnt
                         FROM     users          AS t1
                         GROUP BY snd
                         HAVING   cnt > 1
                         )
                         AS t3
                ON       soundex(t2.fname)=snd
       GROUP BY snd
       );

It's a bit over-complicated, but it works and delivers exactly what you asked for :)

Answer 2

You seem to get what you're asking for - SOUNDEX(fname) would make Soundex hashes only from first name, not whole string. A few of options you can investigate:

SELECT *, COUNT(SOUNDEX(CONCAT(fname, lname))) AS cnt
GROUP BY SOUNDEX(CONCAT(fname, lname))
HAVING cnt > 1;

or

SELECT *, COUNT(SOUNDEX(fname)) AS cnt1, COUNT(SOUNDEX(lname)) AS cnt2
GROUP BY SOUNDEX(fname), SOUNDEX(lname)
HAVING cnt1 > 1 OR cnt2 > 1

It depends on what do you want to achieve: count of similar first name, last names or some synth hash of both.