django数据库基本操作-增删改查（tip）-基本

Posted 2020-09-01 一天一点到

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()