Fastest Way merge two SQLITE Databases

here is one way to merge two database with all tables of the same structure. I hope it could help.

import sqlite3
con3 = sqlite3.connect("combine.db")

con3.execute("ATTACH 'results_a.db' as dba")

con3.execute("BEGIN")
for row in con3.execute("SELECT * FROM dba.sqlite_master WHERE type='table'"):
    combine = "INSERT INTO "+ row[1] + " SELECT * FROM dba." + row[1]
    print(combine)
    con3.execute(combine)
con3.commit()
con3.execute("detach database dba")

Export each database to an SQL dump and then import the dumps into your new combined database.

For GUIs have a look at http://www.sqlite.org/cvstrac/wiki?p=ManagementTools

For example, with SQLiteStudio that will be Database > Export the database: Export format: SQL > Done.

With the command line sqlite3 utility (available in linux repos and often already present ootb) you can create a dump with:

sqlite3 my_database.db .dump > mydump.sql

The SQL dump can be imported directly to a new/existing sqlite database from the shell with:

sqlite3 my_database.db < my_dump.sql