SQLAlchemy的使用---查询的更多操作

# 查询更多操作
from create_table import User, engine
from sqlalchemy.orm import sessionmaker

Session = sessionmaker(engine)
db_session = Session()


# 表达式!!!
# res = db_session.query(User).filter(User.id==4 and User.name ==‘XJ3‘).all()
# print(res[0].name)

# 使用sqlalchemy 自带的and_ or_
from sqlalchemy.sql import and_, or_
ret = db_session.query(User).filter(and_(User.id == 4, User.name==‘XJ3‘)).all()
print(ret)

ret2 = db_session.query(User).filter(or_(User.id == 1, User.name==‘XJ3‘)).all()
print(ret2)

# 只查询id, 起别名
r2 = db_session.query(User.id.label(‘uid‘), User.name).first()
print(r2.uid, r2.name)

# 字符串匹配方式筛选条件
from sqlalchemy.sql import text
r3 = db_session.query(User).filter(text(‘id=:value and name=:name‘)).params(value=4, name=‘XJ3‘)

# 排序
# 正序
user_list = db_session.query(User).order_by(User.id).all()
# 倒序
user_list2 = db_session.query(User).order_by(User.id.desc()).all()