import <a href="https://www.jb51.cc/tag/sql/" target="_blank" class="keywords">sql</a>ite3 class MySum: def __init__(self): self.count = 0 def step(self,value): self.count += value def finalize(self): return self.count con = <a href="https://www.jb51.cc/tag/sql/" target="_blank" class="keywords">sql</a>ite3.connect(":memory:") con.create_aggregate("mysum",1,MySum) cur = con.cursor() cur.execute("create table test(i)") cur.execute("insert into test(i) values (3)") cur.execute("insert into test(i) values (4)") cur.execute("select mysum(i) from test") print cur.fetchone()[0] cur.execute("attach 'z://a.db' as localdb") cur.execute("create table localdb.test as select * from test") cur.execute("insert into localdb.test values (5)") con.commit() con.close