Python update SQLite DB Values
SQL (and thus SQLite) support a variety of operators suitable (amongst others) in UPDATE statements.

This means that you can simplify your whole loop into a single statement:

query = '''
    UPDATE Test SET Test2 = (Test2 + ?), Test3 = (Test3 + ?)
    WHERE Test1 &gt;= 0 AND Test1 &lt; 200
'''
c.execute(query, (200, 400))




Also you should take the habit to use perf_counter instead of time to measure elapsed time. Or use the dedicated timeit module.