输入数据

控制台输入

python manage.py shell进入虚拟环境

1、save插入

>>>from firstApp.models import Topic,Comment

>>>from django.contrib.auth.models import User #save插入方法

>>>user=User.objects.get(username='xym')

>>>topic=Topic(title='four topic',content='this is the four topic',user=user)

>>>topic.save()

>>>comment=Comment(content='so bad',up=123,down=321,topics_id=topic)

>>>comment.save()

2、create插入

>>> user1=User.objects.get(username='xym')
>>> topic_2=Topic.objects.create(title='second topic',content='this is the second topic',user=user1)
>>> coment=Comment.objects.create(content='so good!',up=99,down=33,topics=topic_2)

查询数据

1、get（）查询：返回单实例对象

查询时支持用pk代表主键名称 Topic.objects.get(pk=1)效果一样的

2、get_or_greate()查询：返回tuple对象。当有信息时，会返回查到的信息，并且返回false；没有信息时，则会创建信息，返回true（需要信息完整）

>>> Topic.objects.get_or_create(id=1,title='first topic')
(<Topic: 1:first topic>, False)
>>> Topic.objects.get_or_create(id=1)
(<Topic: 1:first topic>, False)
>>> Topic.objects.get_or_create(id=3)
(<Topic: 3:three>, False)

>>> Topic.objects.get_or_create(id=4,title='four topic',content='this is the four topic!',user=user)
(<Topic: 4:four topic>, True)

3、QuerySet的查询方法：返回可以是零个，一个或者多个

1、all（）方法

>>> Topic.objects.all()
<QuerySet [<Topic: 4:four topic>, <Topic: 3:three>, <Topic: 2:second topic>, <Topic: 1:first topic>]>

>>> print(Topic.objects.all().query)#返回查询过程

SELECT `firstApp_topic`.`id`,

`firstApp_topic`.`create_time`,

`firstApp_topic`.`update_time`,

`firstApp_topic`.`title`,

`firstApp_topic`.`content`,

`firstApp_topic`.`is_online`,

`firstApp_topic`.`user_id`

FROM `firstApp_topic`

ORDER BY `firstApp_topic`.`create_time` DESC

2、reverse方法：逆序打印

>>> Topic.objects.reverse()
<QuerySet [<Topic: 1:first topic>, <Topic: 2:second topic>, <Topic: 3:three>, <Topic: 4:four topic>]>


>>> print(Topic.objects.reverse().query)
SELECT `firstApp_topic`.`id`,
         `firstApp_topic`.`create_time`,
         `firstApp_topic`.`update_time`,
         `firstApp_topic`.`title`,
         `firstApp_topic`.`content`,
         `firstApp_topic`.`is _online`,
         `firstApp_topic`.`user_id`
FROM `firstApp_topic`
ORDER BY  `firstApp_topic`.`create_time` ASC

3、filter过滤方法：相当于sql语句中的where；连接符为双下划线

>>> Topic.objects.filter(id__lte=3)
<QuerySet [<Topic: 3:three>, <Topic: 2:second topic>, <Topic: 1:first topic>]>

查询关键字	含义	相当于where
gt	大于	>
gte	大于等于	>=
lt	小于	<
lte	小于等于	<=
exact	等于	=
iexact	忽略大小写的等于	like xyz
in	是否在集合中	in (a,b)
contains;icontains(忽略大小写)	是否包含	like binary %a%
startswith；istartswith（忽略大小写）	以，，，开头	like binary a%
endswith；iendswith（忽略大小写）	以，，，结尾	like binary %a

4、exclude反向过滤：

>>> Topic.objects.exclude(id__lte=3)
<QuerySet [<Topic: 4:four topic>]>

5、链式查询

>>> Topic.objects.filter(id__lte=3).exclude(title__contains='tle')
<QuerySet [<Topic: 3:three>, <Topic: 2:second topic>, <Topic: 1:first topic>]>
>>> Topic.objects.filter(id__lte=3).exclude(title__contains='tle').filter(content__contains='first')
<QuerySet [<Topic: 1:first topic>]>

查询过程

print(Topic.objects.filter(id__lte=3).exclude(title__contains='tle').filter(content__contains='first').query)

SELECT `firstApp_topic`.`id`,
         `firstApp_topic`.`create_time`,
         `firstApp_topic`.`update_time`,
         `firstApp_topic`.`title`,
         `firstApp_topic`.`content`,
         `firstApp_topic`.`is _online`,
         `firstApp_topic`.`user_id`
FROM `firstApp_topic`
WHERE (`firstApp_topic`.`id` <= 3
        AND NOT (`firstApp_topic`.`title` LIKE BINARY %tle%)
        AND `firstApp_topic`.` content` LIKE BINARY %first%)
ORDER BY  `firstApp_topic`.`create_time` DESC

6、value返回结果：返回指定字段字典数据

>>> Comment.objects.values('id','content')
<QuerySet [{'id': 3, 'content': 'very good!!'}, {'id': 2, 'content': 'good!'}, {'id': 1, 'content': 'very good!'}]>

SELECT `firstApp_comment`.`id`,
         `firstApp_comment`.`content`
FROM `firstApp_comment`
ORDER BY  `firstApp_comment`.`create_time` DESC

7、values_list：返回元组数据

>>> Comment.objects.values_list('id','content')
<QuerySet [(3, 'very good!!'), (2, 'good!'), (1, 'very good!')]>

SELECT `firstApp_comment`.`id`,
         `firstApp_comment`.`content`
FROM `firstApp_comment`
ORDER BY  `firstApp_comment`.`create_time` DESC

（未完，，，，，）

4-数据库操作