django数据库基本操作-增删改查（tip）-基本

补充:django外键保存

                #外键保存
                form_data = Form_Data()
                project, is_created = Project_Name.objects.get_or_create(name=select_text)
                form_data.project = project

1、插入数据

1 Python代码
2 >>> from books.models import Publisher  
3 >>> p1 = Publisher(name='Apress', address='2855 Telegraph Avenue',  
4 ...     city='Berkeley', state_province='CA', country='U.S.A.',  
5 ...     website='http://www.apress.com/')  
6 >>> p1.save()

1 >>> from books.models import Publisher  
2 >>> p1 = Publisher(name='Apress', address='2855 Telegraph Avenue',  
3 ...     city='Berkeley', state_province='CA', country='U.S.A.',  
4 ...     website='http://www.apress.com/')  
5 >>> p1.save()

2、查询

1 Python代码
2 >>> Publisher.objects.all()  
3 [<Publisher: Apress>, <Publisher: O'Reilly>]

1 [python] view plain copy
2 >>> Publisher.objects.all()  
3 [<Publisher: Apress>, <Publisher: O'Reilly>]

获取单个对象：

1 Python代码
2 >>> Publisher.objects.get(name="Apress")  
3 <Publisher: Apress>

1 [python] view plain copy
2 >>> Publisher.objects.get(name="Apress")  
3 <Publisher: Apress>

如果结果是多个对象或者没有返回结果则会抛出异常

3、条件

筛选：

1 Python代码
2 >>> Publisher.objects.filter(name='Apress')  
3 [<Publisher: Apress>]

1 >>> Publisher.objects.filter(name='Apress')  
2 [<Publisher: Apress>]

1 Python代码
2 >>> Publisher.objects.filter(name__contains="press")  
3 [<Publisher: Apress>]

1 [python] view plain copy
2 >>> Publisher.objects.filter(name__contains="press")  
3 [<Publisher: Apress>]

__contains部分会被Django翻译成LIKE语句

排序：

1 Python代码
2 >>> Publisher.objects.order_by("name")  
3 [<Publisher: Apress>, <Publisher: O'Reilly>

1 python] view plain copy
2 >>> Publisher.objects.order_by("name")  
3 [<Publisher: Apress>, <Publisher: O'Reilly>]

相当于 order by name asc

1 Python代码
2 >>> Publisher.objects.order_by("-name")

1 [python] view plain copy
2 >>> Publisher.objects.order_by("-name")

加个负号相当于 order by name desc

限制返回数据：

1 Python代码
2 >>> Publisher.objects.order_by('name')[0]  
3 <Publisher: Apress>

1 [python] view plain copy
2 >>> Publisher.objects.order_by('name')[0]  
3 <Publisher: Apress>

相当于 limit 1

1 Python代码
2 >>> Publisher.objects.order_by('name')[0:2]

1 [python] view plain copy
2 >>> Publisher.objects.order_by('name')[0:2]

相当于 OFFSET 0 LIMIT 2

4、更新

1 Python代码
2 >>> Publisher.objects.filter(id=52).update(name='Apress Publishing')

1 [python] view plain copy
2 >>> Publisher.objects.filter(id=52).update(name='Apress Publishing')

1 Python代码
2 >>> p = Publisher.objects.get(name='Apress') #先查询  
3 >>> p.name = 'Apress Publishing' #更新  
4 >>> p.save()  #保存

1 [python] view plain copy
2 >>> p = Publisher.objects.get(name='Apress') #先查询  
3 >>> p.name = 'Apress Publishing' #更新  
4 >>> p.save()  #保存

5、删除

1 Python代码
2 >>> p = Publisher.objects.get(name="O'Reilly")  
3 >>> p.delete()

1 [python] view plain copy
2 >>> p = Publisher.objects.get(name="O'Reilly")  
3 >>> p.delete()

1 Python代码
2 >>> Publisher.objects.filter(country='USA').delete()

1 [python] view plain copy
2 >>> Publisher.objects.filter(country='USA').delete()