django图书管理系统-外键字段的增删改查

1、创建app02, 并在settings.py里面设置

2、在app02/models.py里面，创建模型

from django.db import models

# Create your models here.

class Book(models.Model):
    name = models.CharField(max_length=32)
    price = models.DecimalField(max_digits=8, decimal_places=2)
    publish_date = models.DateTimeField( auto_now_add= True)
    #添加表关联关系
    publish = models.ForeignKey( to='Publish', on_delete=models.CASCADE )
    authors = models.ManyToManyField( to='Author')


class Publish( models.Model):
    name = models.CharField(max_length=32)
    addr = models.CharField(max_length=64)
    email = models.EmailField()  #内部实现也是charField，定义为EmailField是为了表单校验

class Author(models.Model):
    name = models.CharField(max_length=32)
    age = models.IntegerField()
    #添加表关联关系
    authordetail = models.OneToOneField( to='AuthorDetail', on_delete= models.CASCADE)


#切表，是因为不常用的数据单独放一张表， 对经常用的数据也单独放一张表，提高查询的效率
class AuthorDetail(models.Model):
    addr = models.CharField(max_length=32)
    phone = models.IntegerField()

2、执行makemigrations和migrate, 同步数据库； 然后在对应的表格中添加数据；

给publish出版社表添加数据

 给作者详情表添加数据：

 给作者表添加数据

4、创建项目下创建一个test.py文件，并把manage.py里第一句话复制过来； 然后，可以在test.py里面直接调用模型来操作；

 

5、对Books表外键字段，执行添加数据

import  os
import  sys

if __name__ == "__main__":
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'untitled1.settings')
    import  django
    django.setup()
    from app02 import  models

    #书籍表的增删改查
    #添加数据，方法1
    # models.Book.objects.create( name = "白蛇",price= 66.66,  publish_id = 1 )
    #添加数据，方法2
    publish_obj = models.Publish.objects.filter( pk=3 ).first()
    models.Book.objects.create( name="三体", price = 68.89, publish = publish_obj )

 6、对Books表外键字段，执行修改操作

import  os
import  sys

if __name__ == "__main__":
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'kindeditor_pro.settings')
    import  django
    django.setup()
    from app02 import  models

    #书籍表数据的增加
    #添加数据，方法1
    # models.Book.objects.create( name = "白蛇",price= 66.66,  publish_id = 1 )
    #添加数据，方法2
    # publish_obj = models.Publish.objects.filter( pk=3 ).first()
    # models.Book.objects.create( name="三体", price = 68.89, publish = publish_obj )

    #数据表数据的修改
    #修改数据，方法1
    # models.Book.objects.filter(name="三体").update(publish_id = 2)
    #修改数据，方法2
    publish_obj = models.Publish.objects.filter( pk = 3).first()
    models.Book.objects.filter(name="三体").update(publish = publish_obj)

7、对Books表多对多字段的增加单条数据

import  os
import  sys
from django.db import connection

if __name__ == "__main__":
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'kindeditor_pro.settings')
    import  django
    django.setup()
    from app02 import  models

    #书籍表，外键字段，数据的增加
    #添加数据，方法1
    # models.Book.objects.create( name = "白蛇",price= 66.66,  publish_id = 1 )
    #添加数据，方法2
    # publish_obj = models.Publish.objects.filter( pk=3 ).first()
    # models.Book.objects.create( name="三体", price = 68.89, publish = publish_obj )

    #书籍表，外键字段，数据的修改
    #修改数据，方法1
    # models.Book.objects.filter(name="三体").update(publish_id = 2)
    #修改数据，方法2
    # publish_obj = models.Publish.objects.filter( pk = 3).first()
    # models.Book.objects.filter(name="三体").update(publish = publish_obj)


    #书籍表，多对多字段的增删改查
    book_obj = models.Book.objects.filter(name="三体").first()
    book_obj.authors.add(1)
    print(connection.queries)

执行后，打印的源sql语句为：

[{'sql': 'SELECT @@SQL_AUTO_IS_NULL', 'time': '0.000'},
 {'sql': 'SELECT VERSION()', 'time': '0.001'}, 
{'sql': "SELECT `app02_book`.`id`, `app02_book`.`name`, `app02_book`.`price`, `app02_book`.`publish_date`, `app02_book`.`publish_id` FROM `app02_book` WHERE `app02_book`.`name` = '三体' ORDER BY `app02_book`.`id` ASC LIMIT 1", 'time': '0.000'}, 
{'sql': 'SELECT `app02_book_authors`.`author_id` FROM `app02_book_authors` WHERE (`app02_book_authors`.`book_id` = 1 AND `app02_book_authors`.`author_id` IN (1))', 'time': '0.001'}, 
{'sql': 'INSERT INTO `app02_book_authors` (`book_id`, `author_id`) VALUES (1, 1)', 'time': '0.001'}]

比较重要的一句，样式美化后：

SELECT
    `app02_book`.`id`,
    `app02_book`.`name`,
    `app02_book`.`price`,
    `app02_book`.`publish_date`,
    `app02_book`.`publish_id     
FROM ` app02_book ` WHERE ` app02_book `.` NAME ` = '三体' 
ORDER BY ` app02_book `.` id ` ASC LIMIT 1

 

然后，要注意的地方，插入数据之前，要先检查是否有重复数据，django自动做了重复数据检查的查询操作，所以不会报错；

如果是手动在数据库中插入重复数据会报错，例如，手动再次执行重复插入的操作：

8、对Books表多对多字段的增加多条数据

import  os
import  sys
from django.db import connection

if __name__ == "__main__":
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'kindeditor_pro.settings')
    import  django
    django.setup()
    from app02 import  models

    #书籍表，外键字段，数据的增加
    #添加数据，方法1
    # models.Book.objects.create( name = "白蛇",price= 66.66,  publish_id = 1 )
    #添加数据，方法2
    # publish_obj = models.Publish.objects.filter( pk=3 ).first()
    # models.Book.objects.create( name="三体", price = 68.89, publish = publish_obj )

    #书籍表，外键字段，数据的修改
    #修改数据，方法1
    # models.Book.objects.filter(name="三体").update(publish_id = 2)
    #修改数据，方法2
    # publish_obj = models.Publish.objects.filter( pk = 3).first()
    # models.Book.objects.filter(name="三体").update(publish = publish_obj)


    #书籍表，多对多字段的增加单条数据
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add(1)
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据
    book_obj = models.Book.objects.filter(name="三体").first()
    book_obj.authors.add(1, 2)
    print(connection.queries)

 打印源sql:

[{'sql': 'SELECT @@SQL_AUTO_IS_NULL', 'time': '0.001'}, 
{'sql': 'SELECT VERSION()', 'time': '0.000'}, 
{'sql': "SELECT `app02_book`.`id`, `app02_book`.`name`, `app02_book`.`price`, `app02_book`.`publish_date`, `app02_book`.`publish_id` FROM `app02_book` WHERE `app02_book`.`name` = '三体' ORDER BY `app02_book`.`id` ASC LIMIT 1", 'time': '0.001'}, 
{'sql': 'SELECT `app02_book_authors`.`author_id` FROM `app02_book_authors` WHERE (`app02_book_authors`.`book_id` = 1 AND `app02_book_authors`.`author_id` IN (1, 2))', 'time': '0.002'}, 
{'sql': 'INSERT INTO `app02_book_authors` (`book_id`, `author_id`) VALUES (1, 2)', 'time': '0.001'}]

 9、Book表多对多字段，关联表添加多条数据，方法2

import  os
import  sys
from django.db import connection

if __name__ == "__main__":
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'kindeditor_pro.settings')
    import  django
    django.setup()
    from app02 import  models

    #书籍表，外键字段，数据的增加
    #添加数据，方法1
    # models.Book.objects.create( name = "白蛇",price= 66.66,  publish_id = 1 )
    #添加数据，方法2
    # publish_obj = models.Publish.objects.filter( pk=3 ).first()
    # models.Book.objects.create( name="三体", price = 68.89, publish = publish_obj )

    #书籍表，外键字段，数据的修改
    #修改数据，方法1
    # models.Book.objects.filter(name="三体").update(publish_id = 2)
    #修改数据，方法2
    # publish_obj = models.Publish.objects.filter( pk = 3).first()
    # models.Book.objects.filter(name="三体").update(publish = publish_obj)


    #书籍表，多对多字段的增加单条数据
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add(1)
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法1
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add(1, 2)
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法2
    # author_obj1 = models.Author.objects.filter(id=1).first()
    # author_obj2 = models.Author.objects.filter(id=2).first()
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add( author_obj1, author_obj2 )
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法3
    author_queryset = models.Author.objects.all()
    book_obj = models.Book.objects.filter(name="三体").first()
    book_obj.authors.add( *author_queryset)
    print(connection.queries)

 10、book表多对多字段，关联表删除数据remove方法

import  os
import  sys
from django.db import connection

if __name__ == "__main__":
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'kindeditor_pro.settings')
    import  django
    django.setup()
    from app02 import  models

    #书籍表，外键字段，数据的增加
    #添加数据，方法1
    # models.Book.objects.create( name = "白蛇",price= 66.66,  publish_id = 1 )
    #添加数据，方法2
    # publish_obj = models.Publish.objects.filter( pk=3 ).first()
    # models.Book.objects.create( name="三体", price = 68.89, publish = publish_obj )

    #书籍表，外键字段，数据的修改
    #修改数据，方法1
    # models.Book.objects.filter(name="三体").update(publish_id = 2)
    #修改数据，方法2
    # publish_obj = models.Publish.objects.filter( pk = 3).first()
    # models.Book.objects.filter(name="三体").update(publish = publish_obj)


    #书籍表，多对多字段的增加单条数据
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add(1)
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法1
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add(1, 2)
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法2
    # author_obj1 = models.Author.objects.filter(id=1).first()
    # author_obj2 = models.Author.objects.filter(id=2).first()
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add( author_obj1, author_obj2 )
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法3
    # author_queryset = models.Author.objects.all()
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add( *author_queryset)
    # print(connection.queries)

    #删除书籍对象与作者的绑定关系
    book_obj = models.Book.objects.filter(name="三体").first()
    book_obj.authors.remove(1,2)

 

11、 book表多对多字段，关联表删除数据clear方法

 clear会删除所有绑定关系，不需要传入参数

import  os
import  sys
from django.db import connection

if __name__ == "__main__":
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'kindeditor_pro.settings')
    import  django
    django.setup()
    from app02 import  models

    #书籍表，外键字段，数据的增加
    #添加数据，方法1
    # models.Book.objects.create( name = "白蛇",price= 66.66,  publish_id = 1 )
    #添加数据，方法2
    # publish_obj = models.Publish.objects.filter( pk=3 ).first()
    # models.Book.objects.create( name="三体", price = 68.89, publish = publish_obj )

    #书籍表，外键字段，数据的修改
    #修改数据，方法1
    # models.Book.objects.filter(name="三体").update(publish_id = 2)
    #修改数据，方法2
    # publish_obj = models.Publish.objects.filter( pk = 3).first()
    # models.Book.objects.filter(name="三体").update(publish = publish_obj)


    #书籍表，多对多字段的增加单条数据
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add(1)
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法1
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add(1, 2)
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法2
    # author_obj1 = models.Author.objects.filter(id=1).first()
    # author_obj2 = models.Author.objects.filter(id=2).first()
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add( author_obj1, author_obj2 )
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法3
    # author_queryset = models.Author.objects.all()
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add( *author_queryset)
    # print(connection.queries)

    #删除书籍对象与作者的绑定关系
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.remove(1,2)

    # 清空书籍对象与作者的所有绑定关系
    book_obj = models.Book.objects.filter(name="三体").first()
    book_obj.authors.clear()

 12、 book表多对多字段，关联表修改关联数据

import  os
import  sys
from django.db import connection

if __name__ == "__main__":
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'kindeditor_pro.settings')
    import  django
    django.setup()
    from app02 import  models

    #书籍表，外键字段，数据的增加
    #添加数据，方法1
    # models.Book.objects.create( name = "白蛇",price= 66.66,  publish_id = 1 )
    #添加数据，方法2
    # publish_obj = models.Publish.objects.filter( pk=3 ).first()
    # models.Book.objects.create( name="三体", price = 68.89, publish = publish_obj )

    #书籍表，外键字段，数据的修改
    #修改数据，方法1
    # models.Book.objects.filter(name="三体").update(publish_id = 2)
    #修改数据，方法2
    # publish_obj = models.Publish.objects.filter( pk = 3).first()
    # models.Book.objects.filter(name="三体").update(publish = publish_obj)


    #书籍表，多对多字段的增加单条数据
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add(1)
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法1
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add(1, 2)
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法2
    # author_obj1 = models.Author.objects.filter(id=1).first()
    # author_obj2 = models.Author.objects.filter(id=2).first()
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add( author_obj1, author_obj2 )
    # print(connection.queries)
    # 书籍表，多对多字段的增加多条数据, 方法3
    # author_queryset = models.Author.objects.all()
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.add( *author_queryset)
    # print(connection.queries)

    #删除书籍对象与作者的绑定关系
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.remove(1,2)

    # 清空书籍对象与作者的所有绑定关系
    # book_obj = models.Book.objects.filter(name="三体").first()
    # book_obj.authors.clear()

    #修改书籍对象与作者的所有绑定关系
    book_obj = models.Book.objects.filter(name="三体").first()
    book_obj.authors.set([2,])  #参数必须是可迭代对象； 执行的时候是先清空后添加；

 

 执行后就只剩一条