当我执行 Python 点 py 文件时，它什么也没显示

Question

当我执行下面的代码时，它什么也没显示。 操作系统：窗口 8.1 蟒蛇版本：3.7.4

import os
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker
engine = create_engine("postgresql://postgres:123@127.0.0.1:62621/postgres")
db = scoped_session(sessionmaker(bind=engine))
def main():
flights = db.execute("SELECT origin, destination, duration FROM flights").fetchall() 
for flight in flights:
print(f"{flight.origin} to {flight.destination}, {flight.duration} minutes.")
if __name__ == "__main__":
main()

在此处输入图像描述

Answer 1

你没有执行 main。此块

if __name__ == "__main__":
main()

应该不在主函数

Answer 2

您的缩进在所有代码中都是错误的。尝试这样的事情：

import os
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker
engine = create_engine("postgresql://postgres:123@127.0.0.1:62621/postgres")
db = scoped_session(sessionmaker(bind=engine))
def main():
flights = db.execute("SELECT origin, destination, duration FROM flights").fetchall() 
for flight in flights:
print(f"{flight.origin} to {flight.destination}, {flight.duration} minutes.")
if __name__ == "__main__":
main()

另外，我鼓励你阅读一些关于Python的缩进文档：https://docs.python.org/3/reference/lexical_analysis.html#indentation