Django 07. django框架模型之增删改查基本操作

简介

django框架模型之数据库表增删改查基本操作

1. 生成数据库表结构

models.py

#!/usr/bin/env python

# -*- coding: utf-8 -*-

from __future__ import unicode_literals

from django.db import models

class Blog(models.Model):

name = models.CharField(max_length=100)

tagline = models.TextField()

def __unicode__(self):

return self.name

3. 增

1) 使用创建对象并save()的方法插入一条数据。

F:workSpacePythondjangoTestmodles_test>python manage.py shell

Python 2.7.3 (default, Apr 10 2012, 23:24:47) [MSC v.1500 64 bit (AMD64)] on win32

Type "help", "copyright", "credits" or "license" for more information.

(InteractiveConsole)

>>> from web.models import *

>>> b = Blog(name='Beates Blog', tagline='All the latest Beatles news.')

>>> b.save()

>>>

>>> b.id

1L

>>> b.name

'Beates Blog'

>>> b.tagline

'All the latest Beatles news.'

2) 直接调用create方法插入一条数据不用save。

>>> Blog.objects.create(name='wangZhen Blog', tagline='All the django blog.')

<Blog: wangZhen Blog>

4. 查

1）查出库中所有条数的数据

>>> Blog.objects.all()

2）查询带字段名的所有条数数据

>>> Blog.objects.all().values()

3）查询单条数据

>>> Blog.objects.get(name = 'Beates Blog')

<Blog: Beates Blog>

注意：如果查询的不存在时会报“DoesNotExist”的错

>>> Blog.objects.get(name = 'Beates Blogs')

Traceback (most recent call last):

File "<console>", line 1, in <module>

File "C:Python27libsite-packagesdjangodbmodelsmanager.py", line 85, in manager_method

return getattr(self.get_queryset(), name)(*args, **kwargs)

File "C:Python27libsite-packagesdjangodbmodelsquery.py", line 380, in get

self.model._meta.object_name

DoesNotExist: Blog matching query does not exist.

4）查询匹配条件的多条数据

filter(name='xxx');

filter(name__contains='');

(id__in = [1,2,3]) ;

icontains(大小写无关的LIKE);

startswith和endswith,

range(SQLBETWEEN查询）

'gt', 'in', 'isnull', 'endswith', 'contains', 'lt', 'startswith', 'iendswith', 'icontains','range', 'istartswith'

eg.

>>> Blog.objects.filter(id__in = [1,2])

>>> Blog.objects.filter(id__in = [1,2])[0]

<Blog: Beates Blog>

>>> Blog.objects.filter(id__in = [1,2])[0].name

u'Beates Blog'

>>> Blog.objects.filter(name__startswith = 'w')

<QuerySet [<Blog: wangZhen Blog>]>

>>> Blog.objects.filter(tagline__contains = 'latest')

<QuerySet [<Blog: Beates Blog>]>

>>> Blog.objects.filter(name__icontains = 'blog')

<QuerySet [<Blog: Beates Blog>, <Blog: wangZhen Blog>]>

>>> Blog.objects.filter(name__contains = 'blog')

>>> Blog.objects.filter(id__range=(1,3))

>>> Blog.objects.filter(id__lt = 3, name__icontains = 'wangzhen')

5) 根据字段内容排序后展示数据

根据name字段的内容进行数据排序,会根据字母和数字排序

>>> Blog.objects.order_by('name')

6) 根据字段内容逆向排序后展示数据,加一个负号

>>> Blog.objects.order_by('-name')

7) 连锁查询,先过滤,过滤后进行逆向排序

>>> Blog.objects.filter(id__lt = 2).order_by('-name')

8) 限制数据条数,相当于mysql limit

切片不支持负数,这样就数据序列倒过来的第一条,也就是最后一条数据

>>> Blog.objects.all()

<QuerySet [<Blog: Beates Blog>, <Blog: wangZhen Blog>]>

>>> Blog.objects.all()[1]

<Blog: wangZhen Blog>

5. 删

1）删除表中全部数据

Blog.objects.all().delete()

2）删除一条数据

Blog.objects.get(id = "1").delete()

3) 删除多条数据

Blog.objects.filter(id__gt = 3).delete()

6. 改

1) 修改对象属性并save进行修改

正确：

>>> a = Blog.objects.get(id=1)

>>> a.name = 'test0'

>>> a.save()

>>> Blog.objects.get(id = 1).name

u'test0‘

错误：

>>> Blog.objects.get(id = 1).name = 'test00'

>>> Blog.objects.get(id = 1).save()

>>> Blog.objects.get(id = 1).name

u'test0'

2) 更新多条数据的多个字段或一个字段

>>> Blog.objects.filter(id__in=[1,2]).update(name = 'test')

1L

3) 更新所有数据的多个或一个字段（慎用）（L是line的）

>>> Blog.objects.all().update(name = 'test')

7. 其他

数量：

Blog.objects.all().count()

聚合：

from django.db.models import Min,Max,Sum

Blog.objects.all().aggregate(Max('guest_id'))

原始SQL：

cursor = connection.cursor()

cursor.execute('''SELECT DISTINCT first_name ROM people_person WHERE last_name = %s""", ['Lennon'])

row = cursor.fetchone()

Django 07. django框架模型之增删改查基本操作

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