I'd like to propose to add method SetDistinct() to SqlArray.
Actually, it is a little bit inconvenient to have an SQL statement incorporated into SqlArray. It limits you by letting to use only one table and forces to reimplement all SQL-building API.
Exactly. That is why it is often better to use plain ArrayCtrl
In other words, SqlArray is designed to allow editing data. Distinct breaks this. If you need distinct, you most likely do not want to use SqlArray in the first place.
Using ArrayCtrl for SQL is trivial and very common in SQL apps. Note that you can even use ArrayCtrl as "master" and bind SqlArrays as details.