SQLAlchemy属性常用数据类型--过滤条件

过滤条件

过滤是数据提取的一个很重要的功能，一下对一些常用的过滤条件进行解释，并且这些过滤条件都是只能通过filter方法来实现的。
基本代码：

from sqlalchemy import create_engine, and_, or_
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, Float
from sqlalchemy.orm import sessionmaker
import random

HOSTNAME = '127.0.0.1'
DATABASE = 'demo0417'
PORT = 3306
USERNAME = 'root'
PASSWORD = 'root'

DB_URL = 'mysql+mysqlconnector://{}:{}@{}:{}/{}?charset=utf8'.format(USERNAME, PASSWORD, HOSTNAME, PORT, DATABASE)

engine = create_engine(DB_URL)

Base = declarative_base(engine)

class Article(Base):
    __tablename__ = 'article2'

    id = Column(Integer, primary_key=True, autoincrement=True)
    # title = Column(String(50), nullable=False)
    title = Column(String(50)) # 测试null方法，重新建表
    price = Column(Float, nullable=False)
# def __repr__(self): 方法类似
    def __str__(self):
        return "Article(title:{},price:{})".format(self.title, self.price)

# Base.metadata.drop_all()
Base.metadata.create_all()
Session = sessionmaker(bind=engine)
session = Session()

# for i in range(6):
#     article = Article(title="title%s" % i, price=random.randint(1, 50))
#     session.add(article)
# session.commit()

eq

# eq
# result = session.query(Article).filter(Article.title == 'title3').all()
# for data in result:
#     print(data)

not eq

# not eq  mysql: <>
# result = session.query(Article).filter(Article.title != 'title3').all()
# for data in result:
#     print(data)

like

# like 模糊查询
# result = session.query(Article).filter(Article.title.like('%title%')).all()
# for data in result:
#     print(data)

in

# in
# result = session.query(Article).filter(Article.title.in_(['title1', 'title3'])).all()
# for data in result:
#     print(data)

not in

# not in
# result = session.query(Article).filter(Article.title.notin_(['title2', 'title3'])).all()
# for data in result:
#     print(data)

null

# null != 空
# result = session.query(Article).filter(Article.title == None).all()
# result = session.query(Article).filter(Article.title != None).all()
# result = session.query(Article).filter(Article.title.is_(None)).all()
# result = session.query(Article).filter(Article.title.isnot(None)).all()
#
# for data in result:
#     print(data)

and

# and
# result = session.query(Article).filter(Article.title == 'title3', Article.price == 28).all()
# result = session.query(Article).filter(and_(Article.title == 'title3', Article.price == 28)).all()
# result = session.query(Article).filter(Article.title == 'title3').filter(Article.price == 28).all()
#
# for data in result:
#     print(data)

or

# or
result = session.query(Article).filter(or_(Article.title == 'title3', Article.price == 3)).all()

for data in result:
    print(data)