The principal problem with creating features on the fly is the inability to use a spatial index.
The draw performance is usually sufficiently awful that you'll be willing to jump through the
hoops necessary to have geometries added to the base table.
Note that "Query Layer" is not an Esri term for a view. Query Layers are queries on existing
objects, be they tables or views. If you can construct a view which returns points from
the lon/lat values, then you can make a Query Layer which queries it.
If you want help with the view construction, you'd have to specify what database you're using
(product, version, and sub-release), along with details on your ArcGIS version (including.
service pack) and s full description of the table (and your preferred rowid integer column).
- V