Copying data from one SQLite database to another

Easiest and correct way on a single line:

sqlite3 old.db ".dump mytable" | sqlite3 new.db

The primary key and the columns types will be kept.

You'll have to attach Database X with Database Y using the ATTACH command, then run the appropriate Insert Into commands for the tables you want to transfer.

INSERT INTO X.TABLE SELECT * FROM Y.TABLE;

Or, if the columns are not matched up in order:

INSERT INTO X.TABLE(fieldname1, fieldname2) SELECT fieldname1, fieldname2 FROM Y.TABLE;