Hi,
Try this sql:
insert into {prefix}_social_friends (actor_id, target_id, state, created, modified)
select {#id} as actor_id, user_id, '1' as state, now() as created, now() as modified from {prefix}_social_users
where user_id != {#id}
and {#id} not in (select actor_id from {prefix}_social_friends)
and {#id} not in (select target_id from {prefix}_social_friends);
1. Replace {prefix} with your database table prefix
2. Replace {#id} with the admin user id that you would like to run this script for.
Important:
Do make a backup copy of the table {prefix}_social_friends first before performing this sql.