Yes it's possible if you didn't use AIR specific classes.
I think I've only tried this once or so, so I could be forgetting aspects, but it should be as simple as changing your WindowedApplication tag into an Application tag and plugging the source into a proper Flex project. Because you'd still need to worry about the html template for the Flex version of course, and you also would have a problem if you used any AIR specific classes--they won't be available at all in a flex web app.
The way I'd do this (I guess it's too late for you now) is to do the Flex web app first if possible, and then create the AIR app from that. But you can try the same in reverse. I'd probably create two projects, one AIR project and one Flex project, and move the source from one to the other (changing the Application tag as needed). But someone might have a better way which doesn't require that annoying manual copying and such--I've never done this for a serious project so I haven't thought about all the details too much.
I just create a new project, a Flex app, copy all the files for the project, and change the main app file root tag from WindowedApplication to Application. Flex will tell you if you've used some AIR specific API.
i have used SQLite for Data base..When i changed from air to flex by just changing the WindowApplication to Application.
It is throwing me error while connecting to Database and SQLite statements.
I think your using SQLLite is AIR specific. You may have a bigger job ahead of you, such as using HTTPService to connect to the server side database.
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