在SQLite中，您必须显式打开对外键的支持，否则它将忽略任何与外键相关的SQL.

In SQLite you must turn on support for foreign keys explicitly or it just ignores any SQL related to foreign keys.

engine = create_engine(database_url)

def on_connect(conn, record):
    conn.execute('pragma foreign_keys=ON')

from sqlalchemy import event
event.listen(engine, 'connect', on_connect)