以上运算符都区分大小写，在这些运算符前加上i表示不区分大小写，
如iexact、icontains、istartswith、iendswith.
insert into tb_bookinfo()values()
新增--save
book = BooksInfo(
bookname = '红楼梦',
bookpubtime = date(1930,9,1),
bookauthor = '曹雪芹'
)
character = CharacterInfo(
charactername = '猪八戒',
charactergender = 1,
characterage = 55,
chac_description = '猪悟能',
cbook = book
)
新增--create
CharacterInfo.objects.create(
charactername = '女儿国国王',
charactergender = 1,
characterage = 20,
chac_description = '女儿美',
cbook = book
)
查询多条记录--返回的是列表
BooksInfo.objects.all()
CharacterInfo.objects.all()
查询记录条数
BooksInfo.objects.count()
CharacterInfo.objects.count()
查询单条记录
book = BooksInfo.objects.get(bookname = '西游记')
BooksInfo.objects.get(id=1)
BooksInfo.objects.filter(id__exact=1)
模糊查询
BooksInfo.objects.filter(bookname__contains='梦')
BooksInfo.objects.filter(bookname__endswith='义')
BooksInfo.objects.filter(bookname__startswith='西')
BooksInfo.objects.filter(bookname__istartswith='西')
空查询
BooksInfo.objects.filter(bookname__isnull = False)
范围查询
BooksInfo.objects.filter(id__in=[1,2,4])
属性与常量之间的比较查询：大于，大于等于，小于，小于等于,exclude
BooksInfo.objects.filter(id__gt=3)
BooksInfo.objects.filter(id__gte=2)
BooksInfo.objects.filter(id__lt=3)
BooksInfo.objects.filter(id__lte=3)
BooksInfo.objects.exclude(id=1)
日期查询
year、month、day、week_day、hour、minute、second：对日期时间类型的属性进行运算
BooksInfo.objects.filter(bookpubtime__year=1930)
BooksInfo.objects.filter(bookpubtime__gt=date(1930,9,1))
属性与属性的比较：F(属性名)
from django.db.models import F
BooksInfo.objects.filter(bookcommentcount__gte=F('bookreadcount'))
BooksInfo.objects.filter(bookcommentcount__gte=F('bookreadcount')*2)
and 查询
BooksInfo.objects.filter(bookauthor__contanins='罗',bookname__startswith='三')
or查询Q(属性名__运算符=值)使用&、|连接，&表示逻辑与，|表示逻辑或,~操作符表示非not
BooksInfo.objects.filter(Q(bookreadcount__gt=300)|Q(bookname__contains='吴'))
BooksInfo.objects.filter(~Q(pk=3))
BooksInfo.objects.filter(~Q(id=3))
聚合查询--返回的是字典
BooksInfo.objects.aggregate(Sum('bookreadcount'))
使用count时一般不使用aggregate()过滤器
BooksInfo.objects.count()
排序
BooksInfo.objects.all().order_by('bookreadcount')
BooksInfo.objects.all().order_by('-bookreadcount')
关联查询语法:一到多,多的模型类名小写
一对应的模型类对象.多对应的模型类名小写_set
b = BooksInfo.objects.get(id=1)
b.characterinfo_set.all()
多到一
c = CharacterInfo.objects.get(id=1)
c.cbook
访问一模型的id:多对应的模型类对象.关联类属性_id
c.cbook_id
关联过滤查询：多的模型类名小写
BooksInfo.objects.filter(characterinfo__charactername='贾宝玉')
BooksInfo.objects.filter(characterinfo__charactername__contains='玉')
BooksInfo.objects.filter(characterinfo__characterage__gt=30)
修改：单条修改
c = CharacterInfo.objects.get(charactername='猪八戒')
c.charactername='猪哥哥'
c.save()
批量修改
CharacterInfo.objects.filter(charactername='林黛玉').update(charactername='林妹妹')
删除：
模型类对象delete
c = CharacterInfo.objects.get(id=3)
c.delete()
模型类.objects.filter().delete()
CharacterInfo.objects.filter.(id=14).delete()
Django查询结果集
BooksInfo.objects.all()
BooksInfo.objects.filter(bookreadcount__gt=30).order_by('bookpubtime')
b = BooksInfo.objects.exclude(bookname__contains='三')
确定查询集中是否有数据
b.exists()