SharePoint was once known for it’s unfortunate list of quirky bugs. As of SharePoint 2010 there are definitely less of these to contend with but some still remain – like this one. The sort order for a list view can get rendered incorrectly when editing the view.
When you define a view programmatically it is up to you to create the XML which defines it. A common view query for a tasks list may be to show all items in descending order so that the newest tasks appear at the top of the list. As such:
SPView view = list.Views["All Tasks"]; view.Query = "<OrderBy><FieldRef Name='ID' Ascending='False' /></OrderBy>"; view.Update();
This will update the view just as you or I would expect. However, there is a significant problem here. When a user modifies this view in the future (via the ViewEdit.aspx) the form will show the view is sorted on ID (correct) but the ‘Show items in ascending order’ radio button will be selected (incorrect). If the user now saves the form, perhaps having added another column, the incorrect sort order will be persisted. To avoid this issue you must capitalise the Ascending attribute value as such:
SPView view = list.Views["All Tasks"]; view.Query = "<OrderBy><FieldRef Name='ID' Ascending='FALSE' /></OrderBy>" view.Update();
I’m unaware of anywhere within SharePoint that providing upper-case boolean attributes is bad practice so I would recommend always using FALSE instead of False and TRUE instead of True.