1import sqlite3
2
3class MySum:
4    def __init__(self):
5        self.count = 0
6
7    def step(self, value):
8        self.count += value
9
10    def finalize(self):
11        return self.count
12
13con = sqlite3.connect(":memory:")
14con.create_aggregate("mysum", 1, MySum)
15cur = con.cursor()
16cur.execute("create table test(i)")
17cur.execute("insert into test(i) values (1)")
18cur.execute("insert into test(i) values (2)")
19cur.execute("select mysum(i) from test")
20print(cur.fetchone()[0])
21
22con.close()
23