filter方法常用过滤条件
2024-09-01 15:04:31
#encoding: utf-8 from sqlalchemy import create_engine,Column,Integer,String,Float,func,and_,or_
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from random import randint HOSTNAME = '127.0.0.1' PORT = 3306 DATABASE = 'first_sqlalchemy' USERNAME = 'root' PASSWORD = '' #dialect+driver://username:password@host:port/database
DB_URI = "mysql+pymysql://{username}:{password}@{host}:{port}/" \
"{db}?charset=utf8".format(username=USERNAME,password=PASSWORD,host=HOSTNAME,port=PORT,db=DATABASE) engine = create_engine(DB_URI) Base = declarative_base(engine) # Session = sessionmaker(engine)
# session = Session() session = sessionmaker(engine)() #Session(**local_kw) class Article(Base):
__tablename__ = 'article' id = Column(Integer,primary_key=True,autoincrement=True) title = Column(String(50),nullable=False) price = Column(Float,nullable=False) content = Column(String(100)) def __repr__(self):
return '<Article(title:%s)>'%self.title # Base.metadata.drop_all()
#
# Base.metadata.create_all()
#
# for x in range(6):
# article = Article(title='title%s'%x,price=randint(0,100))
# session.add(article)
# session.commit() # 1、equal 等于的意思
article = session.query(Article).filter(Article.id == 1).first() article_title = session.query(Article).filter(Article.title == 'title1').first()
print(article)
print(article_title) # 2、not equal 不等于的意思 article_title_not_equal = session.query(Article).filter(Article.title != 'title0').all() print(article_title_not_equal) #3、like #注意:如果不查询,直接打印显示原生sql,不用first()或 all()方法
article_title_like = session.query(Article).filter(Article.title.like('title%') ).all()
#相当于sql select * from article where title like '%title%'; print(article_title_like)
#插入一条数据的sql :insert into article values(null,'abc','100'); # 4、ilike(不区分大小写)
article_title_ilike = session.query(Article).filter(Article.title.ilike('title%') )
print(article_title_ilike)
#SELECT article.id AS article_id, article.title AS article_title, article.price AS article_price FROM article
# WHERE lower(article.title) LIKE lower(%(title_1)s) # 5、in (在某某里面) #为什么用in_,因为要避开关键字in
article_title_in = session.query(Article).filter(Article.title.in_(['title1','title2'])).all() print(article_title_in) #原生sql SELECT article.id AS article_id, article.title AS article_title, article.price AS article_price
# FROM article
# WHERE article.title IN (%(title_1)s, %(title_2)s)%('title1','title2'),这是格式化字符串,防止sql注入 #6、not in (不在某某里面) article_title_not_in = session.query(Article).filter(Article.title.notin_(['title1','title2'])).all() print(article_title_not_in) #not in (另一种写法) ~取反的意思 article_title_not_in_1 = session.query(Article).filter(~Article.title.in_(['title1','title2'])).all() print(article_title_not_in_1) # 7、is null 判断某个字段是否为空 # alter table article add column content text; 添加一列,
# 修改原先好的类别 alter table article modify column content varchar(100);
# update article set content='python or go' where id =7; 修改一条记录 is_null_content = session.query(Article).filter(Article.content == None).all() print(is_null_content) # not is null 不为空 not_is_null_content = session.query(Article).filter(Article.content != None) print(not_is_null_content) '''
SELECT article.id AS article_id, article.title AS article_title, article.price AS article_price,
article.content AS article_content
FROM article
WHERE article.content IS NOT NULL
''' #8、and 和 title_and_content = session.query(Article).\
filter(Article.title == 'python or go',Article.content == 'python or go').all()
print(title_and_content) #另一种显示方式 title_and_content_1 = session.query(Article).\
filter(and_(Article.title == 'python or go',Article.content == 'python or go'))
print(title_and_content_1) #原生sql显示SELECT article.id AS article_id, article.title AS article_title,
# article.price AS article_price, article.content AS article_content
# FROM article
# WHERE article.title = %(title_1)s AND article.content = %(content_1)s #9.or
title_or_content = session.query(Article).filter\
(or_(Article.title == 'python or go',Article.content == 'python or go')).all()
print(title_or_content)
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