django数据库基本操作增删改查
1、插入数据
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>>> 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
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>>> Publisher.objects.all()
[<Publisher: Apress>, <Publisher: O'Reilly>]
获取单个对象：
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>>> 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：
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>>> Publisher.objects.filter(name='Apress')
[<Publisher: Apress>]
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>>> Publisher.objects.filter(name__contains="press")
[<Publisher: Apress>]
__contains部分会被Django翻译成LIKE语句
排序：
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>>> Publisher.objects.order_by("name")
[<Publisher: Apress>, <Publisher: O'Reilly>]
相当于 order by name asc
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>>> Publisher.objects.order_by("-name")
加个负号相当于 order by name desc
限制返回数据：
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>>> Publisher.objects.order_by('name')[0]
<Publisher: Apress>
相当于 limit 1
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>>> Publisher.objects.order_by('name')[0:2]
相当于 OFFSET 0 LIMIT 2
4、更新
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>>> Publisher.objects.filter(id=52).update(name='Apress Publishing')
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>>> p = Publisher.objects.get(name='Apress') #先查询
>>> p.name = 'Apress Publishing' #更新
>>> p.save() #保存
5、删除
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>>> p = Publisher.objects.get(name="O'Reilly")
>>> p.delete()
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>>> Publisher.objects.filter(country='USA').delete()