If you have a date stored as seconds (not milliseconds*) since The Epoch, you can convert it to a more readable date in SQLite through the strftime function. An example would be, "strftime("%Y-%m-%d",date,'unixepoch')".
Since the Date object in AS3 has the getTime method returning milliseconds since The Epoch, you'd just need to either divide by 1000 before saving it in a SQLite DB, or divide by 1000 inside the call to strftime.