Re: Copying data from one table to another - how to specify fields?

I've also tried renaming 'Alex' to a temp. value:

# update drupal_users set name='Alex_1972' where name='Alex';
UPDATE 1

# INSERT INTO drupal_users (uid, name, mail, created, access)
SELECT user_id, username, user_email, user_regdate, user_lastvisit
FROM phpbb_users
WHERE user_id > 50 and length(username) > 0 and username <> 'Alex';
ERROR: duplicate key value violates unique constraint "drupal_users_name_key"

# select username, user_id from phpbb_users where exists
(select 1 from drupal_users
where drupal_users.name = phpbb_users.username);
username | user_id
----------+---------
(0 rows)

so there must be a duplicated username in the source table
phpbb_users, but how could I find that record?

Thank you
Alex