使用SQLAlchemy操作数据库表过程解析

# -*- coding:utf-8 -*-
from sqlalchemy import create_engine,MetaData,Table,exists
from sqlalchemy.orm import sessionmaker, scoped_session
from util.Log import Log
from conf.parseConfig import parseConf
# 从配置文件中获取mysql的配置信息
host = parseConf.get_conf('MySQLInfo', 'host')
port = parseConf.get_conf('MySQLInfo', 'port')
dbname = parseConf.get_conf('MySQLInfo', 'dbname')
usernm = parseConf.get_conf('MySQLInfo', 'usernm')
passwd = parseConf.get_conf('MySQLInfo', 'passwd')

engine_str = "mysql+mysqlconnector://{0}:{1}@{2}:{3}/{4}".format(usernm, passwd, host, port, dbname)


class OpsMysql(object):
  def __init__(self, log=Log(__file__).getlog()):
    self.log = log
    self.session = None
    try:
      self.engine = create_engine(
        engine_str,
        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）
        # echo=True, # 显示相应执行的 sql 指令
        encoding='utf-8'
      )
      SessionFactory = sessionmaker(bind=self.engine)
      self.session = scoped_session(SessionFactory)
    except Exception as e:
      self.log.error(str(e))
      self.log.error("Connect {0}@{1}:{2} failed!".format(dbname, host, port))

  def get_session(self):
    return self.session

  def getEngine(self):
    return self.engine

  def init_db(self, base):
    base.metadata.create_all(self.engine)

  def drop_db(self, base):
    base.metadata.drop_all(self.engine)


if __name__ == "__main__":
  log = Log(__file__).getlog()
  tt = OpsMysql(log)
  session = tt.get_session()
  
  if session:
    # 通过执行原生的sql语句实现操作已有的表
    # 此处演示了向原生sql语句传递变量的用法 即动态执行sql语句 更加灵活
    mail_id = 1
    res = session.execute('select * from tbl_mail_addr where mail_id='" + mail_id + "' and mail_tp="c"')
    res01 = res.fetchall() # 结果是列表
    print(res01[0])
    # (1, 'c', 1, 'XX@u163.com')
    
    mail_id = '1'
    mail_type = 'c'
    # 查询id为1，类型是c的邮箱信息，并按mail_tp降序，addr_no升序排列，限制查询数量100
    sql = "select * from tbl_mail_addr where tbl_mail_addr.oper_flag='1' and tbl_mail_addr.mail_id='" + mail_id + "' and tbl_mail_addr.mail_tp='" + mail_type + "' order by tbl_mail_addr.mail_tp, tbl_mail_addr.addr_no ASC limit 100"
    result = session.execute(sql)
    value_list = result.fetchall()
    print(value_list)
    # [(1, 'c', 1, 'XX@163.com'), (1, 'c', 2, 'XX@qq.com), (1, 'c', 3, 'XX@qq.com')]

  session.close()