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()