使用sqlalchemy的postgresql连接错误

Question

import os

from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker

engine = create_engine("postgresql://postgres:114920@localhost/Databases")
db = scoped_session(sessionmaker(bind=engine))

def main():
    Railway = db.execute("SELECT origin, destination, duration FROM Railway").fetchall()
    for railway in Railway:
        print(f"{railway.origin} to {railway.destination}, {railway.duration} minutes")

if __name__ == "__main__":
    main()

我犯了这个错误 （如果可能的话，请分享我被困在这个敌人很长时间的代码）

C:\Web Development\Lecture02>python hoja1.py Traceback (most recent call last): File "C:\Web Development\Lecture02\hoja1.py", line 6, in engine = create_engine("postgresql://postgres:114920@localhost/Databases") File "C:\Users\hp\AppData\Local\Programs\Python\Python39\lib\site-packages\sqlalchemy\engine_init_.py", line 500, in create_engine return strategy.create(*args, **kwargs) File "C:\Users\hp\AppData\Local\Programs\Python\Python39\lib\site-packages\sqlalchemy\engine\strategies.py", line 87, in create dbapi = dialect_cls.dbapi(**dbapi_args) File "C:\Users\hp\AppData\Local\Programs\Python\Python39\lib\site-packages\sqlalchemy\dialects\postgresql\psycopg2.py", line 778, in dbapi import psycopg2 ModuleNotFoundError: No module named 'psycopg2'

Answer 1

import os

从sqlalchemy导入创建引擎 从sqlalchemy.orm导入作用域的_会话，sessionmaker

引擎=创建引擎（“postgresql://postgres:114920@本地主机：5432/postgres） db=作用域_会话（sessionmaker（bind=engine））

def main（）： Railway=db.execute（“从铁路中选择起点、终点、持续时间”）.fetchall（） 对于铁路中的铁路： 打印（f“{railway.origin}到{railway.destination}，{railway.duration}分钟”）

如果name==“main”： main（）

Answer 2

看起来你没有psycopg2模块 尝试pip安装psycopg2 在终端中运行此命令

pip install psycopg2