Question

Possible Duplicate:
How to Join three tables

I have 4 tables :

• folder (id_folder,name)
• subfolder(id_subfolder,id_folder,name,othercolumn,…)
• piece(id_piece,id_subfolder,id_folder)
• image(id_image,id_piece,name,..)

How can I get all the contents of one folder (“id_folder=1” for example)?

Answer 1

You would JOIN your tables, something like this:

select *
from folder f
left join subfolder sf
    on f.id_folder = sf.id_folder
left join piece p
    on sf.id_subfolder = p.id_subfolder
    and sf.id_folder = p.id_folder
left join image i
    on p.id_piece = i.id_piece
where f.id_folder = 1

If you need help learning JOIN syntax, then there is a great Visual Explanation of SQL Joins that will help.