请问做ppt换模板在哪里/(ppt做好了如何换模板)
658
2022-05-30
Pony is an advanced object-relational mapper
文档:
PyPI: https://pypi.org/project/pony/
Github: https://github.com/ponyorm/pony
doc: https://docs.ponyorm.org/
安装
pip install pony
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代码实例
# -*- coding: utf-8 -*- from pony.orm import Database, db_session, Required, Set, select, set_sql_debug # 创建数据库对象 db = Database() # 建立数据库连接 db.bind(provider='sqlite', filename=':memory:') # 开启debug,打印sql set_sql_debug(True) # 建立实体类 class Person(db.Entity): name = Required(str) age = Required(int) cars = Set('Car') class Car(db.Entity): make = Required(str) model = Required(str) owner = Required(Person) # 建表 db.generate_mapping(create_tables=True) """ CREATE TABLE "Person" ( "id" INTEGER PRIMARY KEY AUTOINCREMENT, "name" TEXT NOT NULL, "age" INTEGER NOT NULL ) CREATE TABLE "Car" ( "id" INTEGER PRIMARY KEY AUTOINCREMENT, "make" TEXT NOT NULL, "model" TEXT NOT NULL, "owner" INTEGER NOT NULL REFERENCES "Person" ("id") ON DELETE CASCADE ) SELECT "Car"."id", "Car"."make", "Car"."model", "Car"."owner" FROM "Car" "Car" WHERE 0 = 1 SELECT "Person"."id", "Person"."name", "Person"."age" FROM "Person" "Person" WHERE 0 = 1 """ # 插入数据 with db_session: p1 = Person(name='John', age=20) p2 = Person(name='Mary', age=22) p3 = Person(name='Bob', age=30) c1 = Car(make='Toyota', model='Prius', owner=p2) c2 = Car(make='Ford', model='Explorer', owner=p3) """ INSERT INTO "Person" ("name", "age") VALUES (?, ?) ['John', 20] INSERT INTO "Person" ("name", "age") VALUES (?, ?) ['Mary', 22] INSERT INTO "Person" ("name", "age") VALUES (?, ?) ['Bob', 30] INSERT INTO "Car" ("make", "model", "owner") VALUES (?, ?, ?) ['Toyota', 'Prius', 2] INSERT INTO "Car" ("make", "model", "owner") VALUES (?, ?, ?) ['Ford', 'Explorer', 3] """ # 更新数据 with db_session: p = Person.get(id=2) # 使用get来获取一条数据,如果没有查到会返回None p.name = "new name" """ SELECT "id", "name", "age" FROM "Person" WHERE "id" = ? [2] UPDATE "Person" SET "name" = ? WHERE "id" = ? ['new name', 2] """ # 查询数据 with db_session: for person in select(p for p in Person if p.age > 20)[:]: print(person.name, person.age, person.cars) """ SELECT "p"."id", "p"."name", "p"."age" FROM "Person" "p" WHERE "p"."age" > 20 SELECT "id", "make", "model", "owner" FROM "Car" WHERE "owner" = ? [2] SELECT "id", "make", "model", "owner" FROM "Car" WHERE "owner" = ? [3] """
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参考
只有 Python 魔法少女才知道的 PonyORM
抛弃丑陋,拥抱优雅–Pythonic的Pony ORM
Python
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