I am running the nested query
SELECT Id, Name, Account.Name,
(SELECT Id, OrderItemNumber, Product2.Name
FROM OrderItems)
FROM Order
This is only 1 level deep. Is there an example which can show me how to make a 3 to 5 level deep select in SOQL ?
SOQL is limited in that subqueries like you show are only allowed at a single level.
However, you can go higher (5 levels) if you do bottom up.
E.g. we rewrite your query like so:
SELECT Id, OrderItemNumber, Product2.Name,
Order.Id, Order.Name, Order.Account.Name,
Order.Account.Parent.Name,
Order.Account.Parent.Parent.Name,
Order.Account.Parent.Parent.Parent.Name,
Order.Pricebook2.Name
FROM OrderItem
To get some account hierarchy. It's clunky as SOQL is, but you get the idea