You should really change your DB design to something like this
pictures table
--------------
id
name
users table
-----------
id
name
birth_date
user_pictures table
-------------------
picture_id
user_id
The user_pictures
table would contain a record for every user-picture relation.
Example data
pictures
id name
1 dsc_01.jpg
2 dsc_04.jpg
users
id name
1 tom
2 jane
user_pictures
picture_id user_id
1 1
1 2
2 2
You can then select all pictures a specfic user is accociated with like this
select p.name
from pictures p
join user_pictures up on up.picture_id = p.id
join users u on up.user_id = u.id
where u.name = 'tom'