[swuecho]

in python 3.6

    import sqlite3
    import json

    def delta(*args):
        ret = {}
        for name, old, new in zip(args[::3], args[1::3], 
            args[2::3]):
            if old != new:
               ret[name] = old
        if ret:
           return json.dumps(ret)

    db = sqlite3.connect(':memory:')

    db.create_function('delta1',3, delta)
    db.create_function('delta2',6, delta)
    db.create_function('delta3',9, delta)
    print(db.execute('select delta2("b", 20, 20, "c", 3.4, 
    3.6)').fetchone())
    # ('{"c": 3.4}',)