1、low方法:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
(1)person_obj=session.query(Person).filter(Person.name=='jack') print (person_obj.count()) (2)person_obj=session.query(Person).filter(Person.name=='jack').fist()
2、高级用法:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
from sqlalchemy.sql import exists 1.ret = self.session.query(exists().where(db_models.User.name == 'jack')).scalar() 2.self.session.query(db_models.User).filter_by(name='John Smith').exists() ).scalar()