I have a table "Orders" with the following columns:

• Id
• Created (Date)
• Modified (Date)

An order always has Created date but might have or not have Modified date. Here is an example

1. 1, 2019-12-24, null
2. 2, 2019-03-13, 2020-01-10
3. 3, 2019-02-10, 2019-02-25
4. 4, 2019-01-10, null

How can I create a query that will order the orders chronologically by last interaction with them? In the example above the result should be 4, 3, 1, 2?

If I do orders.OrderBy(o => o.Modified).ThenBy(o => o.Created) the nulls will be 4, 1, 3, 2 because of the nulls. If I ignore them using first OrderBy(o => o.Modified.HasValue) then those entities will be put either in the beginning or in the end.

CodePudding user response：

Try this approach:

orders.OrderBy(o => o.Modified ?? o.Created);