Nested Query Loop

I have a query that I want to loop over the data and display. The query is an inner join with one table being order numbers and the second being details on each order. They are joined by the order number. What i am trying to do is loop over the data and group all the details under the order number. I have tried numerous nesting configurations and I have had no luck. This is what I would like to see.

Order Number 1
Item 1
Item 2
Item 3

Order Number 2
Item 1
Item 2

Order Number 3
item 1
Item 2
Item 3
Item 4

Any recomendations?