Return product category with hierarchical info

Good afternoon (o;

First of all, am I am totally no expert in using PGSQL but use it mainly
for simple web applications...

Now I have a table which represents the categories for products in a
hierarchical manner:

    id | name | parent

So a top category is represented with parent being 0:

    1 | 'Living' | 0

The next level would look:

    2 | 'Decoration' | 1

And the last level (only 3 levels):

    3 | 'Table' | 2

So far I'm using this query to get all 3rd level categories as I use the
output for datatables editor as a product can only belong to the lowest
category:

select id, name from category
where parent in (select id from category where parent in (select id from
category where parent = 0))

But this has a problem as more than one 3rd level category can have the
same name, therefore difficult to distinguish in the datatables editor
which one is right.

So now my question (finally ;o):

Is there a simple query that would return all 3rd levels category ids
and names together with the concatenated names of the upper levels?
Something like:

    3 | 'Table' | 'Living - Decoration'

thanks in advance

richard

PS: If someone could recommend a good ebook or online resource for such
stupid questions, even better (o;