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

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

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

2、查询

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

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

获取单个对象：

 

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

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

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

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

 

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

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

__contains部分会被Django翻译成LIKE语句

 

排序：

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

 

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

 

 

相当于 order by name asc

 

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

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

 

加个负号相当于 order by name desc

 

限制返回数据：

 

 

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

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

 

相当于 limit 1

 

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

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

相当于 OFFSET 0 LIMIT 2

 

4、更新

 

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

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

 

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

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

 

 

5、删除

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

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

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

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