Django之ORM练习

Posted 2021-01-10 mjc69213

一、表结构

# 书
class Book(models.Model):
    title = models.CharField(max_length=32)
    publish_date = models.DateField(auto_now_add=True)
    price = models.DecimalField(max_digits=5, decimal_places=2)
    memo = models.TextField(null=True)
    # 创建外键，关联publish
    publisher = models.ForeignKey(to="Publisher")
    # 创建多对多关联author
    author = models.ManyToManyField(to="Author")

    def __str__(self):
        return "<Book object: {} {}>".format(self.id, self.title)


# 出版社
class Publisher(models.Model):
    name = models.CharField(max_length=32)
    city = models.CharField(max_length=32)

    def __str__(self):
        return "<Publisher object: {} {}>".format(self.id, self.name)


# 作者
class Author(models.Model):
    name = models.CharField(max_length=32)
    age = models.IntegerField()
    phone = models.CharField(max_length=11)

    def __str__(self):
        return "<Author object: {} {}>".format(self.id, self.name)

二、数据

-- ----------------------------
-- Records of app01_author
-- ----------------------------
INSERT INTO `app01_author` VALUES (‘1‘, ‘金老板‘, ‘18‘, ‘15512351234‘);
INSERT INTO `app01_author` VALUES (‘2‘, ‘小哪吒‘, ‘20‘, ‘15312341234‘);
INSERT INTO `app01_author` VALUES (‘3‘, ‘Alex‘, ‘73‘, ‘15512341234‘);

-- ----------------------------
-- Records of app01_publisher
-- ----------------------------
INSERT INTO `app01_publisher` VALUES (‘1‘, ‘沙河出版社‘, ‘北京‘);
INSERT INTO `app01_publisher` VALUES (‘2‘, ‘西二旗出版社‘, ‘北京‘);
INSERT INTO `app01_publisher` VALUES (‘3‘, ‘张江出版社‘, ‘上海‘);
INSERT INTO `app01_publisher` VALUES (‘4‘, ‘沙河出版社‘, ‘上海‘);

-- ----------------------------
-- Records of app01_book
-- ----------------------------
INSERT INTO `app01_book` VALUES (‘1‘, ‘跟金老板学开车‘, ‘2018-08-03‘, ‘12.90‘, null, ‘1‘);
INSERT INTO `app01_book` VALUES (‘2‘, ‘跟金老板学开潜艇‘, ‘2017-08-10‘, ‘9.99‘, null, ‘1‘);
INSERT INTO `app01_book` VALUES (‘3‘, ‘跟老男孩学思想‘, ‘2018-09-03‘, ‘39.99‘, null, ‘2‘);
INSERT INTO `app01_book` VALUES (‘4‘, ‘跟egon学喊麦‘, ‘2018-06-12‘, ‘0.99‘, null, ‘4‘);

-- ----------------------------
-- Records of app01_book_author
-- ----------------------------
INSERT INTO `app01_book_author` VALUES (‘3‘, ‘1‘, ‘1‘);
INSERT INTO `app01_book_author` VALUES (‘4‘, ‘1‘, ‘2‘);
INSERT INTO `app01_book_author` VALUES (‘5‘, ‘2‘, ‘1‘);
INSERT INTO `app01_book_author` VALUES (‘2‘, ‘2‘, ‘2‘);
INSERT INTO `app01_book_author` VALUES (‘6‘, ‘3‘, ‘3‘);
INSERT INTO `app01_book_author` VALUES (‘7‘, ‘4‘, ‘3‘);

 三、练习题目 

查找所有书名里包含金老板的书
查找出版日期是2018年的书
查找出版日期是2017年的书名
查找价格大于10元的书
查找价格大于10元的书名和价格
查找memo字段是空的书

查找在北京的出版社
查找名字以沙河开头的出版社

查找“沙河出版社”出版的所有书籍
查找每个出版社出版价格最高的书籍价格
查找每个出版社的书名以及出的书籍数量

查找作者名字里面带“小”字的作者
查找年龄大于30岁的作者
查找手机号是155开头的作者
查找手机号是155开头的作者的姓名和年龄

查找每个作者写的价格最高的书籍价格
查找每个作者的姓名以及出的书籍数量

查找书名是“跟金老板学开车”的书的出版社
查找书名是“跟金老板学开车”的书的出版社所在的城市
查找书名是“跟金老板学开车”的书的出版社的名称
查找书名是“跟金老板学开车”的书的出版社出版的其他书籍的名字和价格

查找书名是“跟金老板学开车”的书的所有作者
查找书名是“跟金老板学开车”的书的作者的年龄
查找书名是“跟金老板学开车”的书的作者的手机号码
查找书名是“跟金老板学开车”的书的作者们的姓名以及出版的所有书籍名称和价钱

四、答案

#! /usr/bin/env python3
# -*- coding: utf-8 -*-

import os

if __name__ == ‘__main__‘:
    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "day03.settings")
    import django
    django.setup()

    from app01 import models
    from django.db.models import Avg, Max, Min, Count

    # print(models.Book.objects.filter(author__name=‘金老板‘))
    # print(models.Book.objects.filter(publish_date__year=2018))
    # print(models.Book.objects.filter(publish_date__year=2017))
    # print(models.Book.objects.filter(price__gt=10))
    # print(models.Book.objects.filter(price__gt=10).values(‘price‘, ‘title‘))
    # print(models.Book.objects.filter(memo__isnull=True))
    # print(models.Publisher.objects.filter(city=‘北京‘))
    # print(models.Publisher.objects.filter(name__istartswith=‘沙河‘))
    # print(models.Book.objects.filter(publisher__name__istartswith=‘沙河‘))
    # print(models.Book.objects.values(‘publisher__name‘).annotate(max_price = Max(‘price‘)).values(‘title‘, ‘publisher__name‘, ‘max_price‘))
    # print(models.Book.objects.values(‘publisher__name‘).annotate(count=Count(‘id‘)).values(‘title‘, ‘count‘))
    # print(models.Author.objects.filter(name__contains=‘小‘).values())
    # print(models.Author.objects.filter(phone__istartswith=155).values_list())
    # print(models.Author.objects.filter(phone__istartswith=155).values_list(‘name‘, ‘age‘))
    # print(models.Book.objects.values(‘author__name‘).annotate(max=Max(‘price‘)).values(‘title‘, ‘price‘))
    # print(models.Author.objects.values(‘name‘).annotate(count=Count(‘book__id‘)).values(‘name‘,‘count‘))
    # print(models.Book.objects.filter(title=‘跟金老板学开车‘).values(‘publisher__name‘))
    # print(models.Book.objects.filter(title=‘跟金老板学开车‘).values_list(‘publisher__city‘))
    # print(models.Book.objects.filter(title=‘跟金老板学开车‘).values(‘publisher__name‘))
    # print(models.Publisher.objects.filter().exclude(book__title=‘跟金老板学开车‘).values(‘book__title‘, ‘book__price‘))
    # print(models.Book.objects.filter(title=‘跟金老板学开车‘).values(‘author__name‘))
    # print(models.Author.objects.filter(book__title=‘跟金老板学开车‘).values(‘name‘,‘age‘))
    # print(models.Publisher.objects.filter(book__title=‘跟金老板学开车‘).values(‘book__author__name‘, ‘book__author__phone‘))
    # ret = models.Book.objects.filter(title=‘跟金老板学开车‘).values_list(‘author__name‘)
    # for i in ret:
    #     print(models.Book.objects.filter(author__name=i[0]).values_list(‘author__name‘,‘title‘,‘price‘))