The easiest solution is to create all objects on each level in advance, and then pick and activate them one-by-one when needed. If there are not too many objects, you can do this manually in layout editor - say, add 10 asteroids, 10 enemy1, 5 enemy2, 1 boss etc.
Add them all to a family. Every 1000px pick a random family member, move it to the screen and activate its behaviors.
With a large number of objects you can still do something similar:
On Start of layout
Repeat 100 times: Create asteroid at (-9999,-9999)
Repeat 200 times: Create enemy1 at (-9999,-9999)
....
For a large number of levels you can use an array or JSON. I'm not sure about SQLLite, it will probably be an overkill.
I actually find it easier to enter data in table format in the Array Editor (or you can copy from Excel), and then convert the array to JSON in runtime:
Each level in the array is on a separate sheet.