Python的ORM框架Peewee使用入门(三)

我们不要认为这颗行星上的一切都是理所当然的

检索数据

from datetime import datefrom peewee import *db = SqliteDatabase('people.db')class Person(Model):    name = CharField()    birthday = DateField()    is_relative = BooleanField()    class Meta:        database = db   #用了“people.db”数据库class Pet(Model):    owner = ForeignKeyField(Person, related_name='pets')    name = CharField()    animal_type = CharField()    class Meta:     database = db  #用了“people.db”数据库"""-------------------------------------------------------------------------------------------------------"""#获取单个数据记录grandma = Person.select().where(Person.name == 'Grandma L.').get()"""同上"""grandma = Person.get(Person.name == 'Grandma L.')#获取数据列表"""for person in Person.select():    print("人名:",person.name, person.is_relative)query = Pet.select().where(Pet.animal_type == 'cat')for pet in query:    print("宠物名:",pet.name, "主人名:",pet.owner.name)"""#连接查询"""query = (Pet.select(Pet, Person)         .join(Person)         .where(Pet.animal_type == 'cat'))for pet in query:     print(pet.name, pet.owner.name)"""#让我们获取Bob拥有的所有宠物for pet in Pet.select().join(Person).where(Person.name == 'Bob'):      print(pet.name)"""同上"""uncle_bob = Person(name='Bob', birthday=date(1960, 1, 15), is_relative=True)for pet in Pet.select().where(Pet.owner == uncle_bob).order_by(Pet.name):      print(pet.name)#日期排序for person in Person.select().order_by(Person.birthday.desc()):     print(person.name, person.birthday)"""-------------------------------------------------------------------------------------------------------"""for person in Person.select():     print(person.name, person.pets.count(), 'pets')     for pet in person.pets:          print ('    ', pet.name, pet.animal_type)"""-------------------------------------------------------------------------------------------------------"""#日期条件查询d1940 = date(1940, 1, 1)d1960 = date(1960, 1, 1)#查询生日大于1960年，小于1940年query = (Person.select()        .where((Person.birthday < d1940) | (Person.birthday > d1960)))for person in query:     print(person.name, person.birthday)#查询生日在1940年与1960年 之间的人query = (Person         .select()        .where((Person.birthday > d1940) & (Person.birthday < d1960)))for person in query:    print(person.name, person.birthday)"""------------------------------------------------------"""#查询人名,g开头的expression = (fn.Lower(fn.Substr(Person.name, 1, 1)) == 'g')for person in Person.select().where(expression):     print(person.name)"""连接数据库连接"""db.close()