from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session
from sqlalchemy.orm import sessionmaker
from urllib.parse import quote_plus as urlquote
userName = 'test'
password = 'TEST@1234567'
dbHost = '127.0.0.1'
dbPort = 3306
dbName = 'dbtest'

DB_CONNECT = f'mysql+pymysql://{userName}:{urlquote(password)}@{dbHost}:{dbPort}/{dbName}?charset=utf8'


engine = create_engine(
        DB_CONNECT,
        max_overflow=0,  # 超过连接池大小外最多创建的连接
        pool_size=5,  # 连接池大小
        pool_timeout=30,  # 池中没有线程最多等待的时间，否则报错
        pool_recycle=-1  # 多久之后对线程池中的线程进行一次连接的回收（重置）
    )
SessionFactory = sessionmaker(bind=engine)
session = scoped_session(SessionFactory)

cursor = session.execute('select username from sys_user')
result = cursor.fetchall()
for i in result:    
    print(i)