anybody can help me with SQL?

I have a database with 3 tables, 'Group', 'Category', and 'Expense'

This is to be used in a program to manage expenses.
one group has many category, one category has many expense.. What i need is an SQL to get all of the group details, category details and expenses details.
I joinned these three tables, however if a group that doesnt contains any category or it's category doesnt has any expense record, the SQL result does not return them.. is there a way to do that?
like giving back with all of the category and expenses details "NULL" other than dont return anything at all.. like giving null value instead?!

Is hard one.. I think i had heard some function in sql can do but i dont really sure and rememeber.. thx guys!!!

Use outer joins as shown in example below, but this might be not a proper solution of your query. I believe it will give you an idea to write your own query effeciently.

SELECT column1, column2, column3
FROM Group LEFT OUTER JOIN Category
ON <join condition>
LEFT OUTER JOIN Expenses
ON <join condition>

Regards,