orm——13
import os if __name__ == '__main__': os.environ.setdefault("DJANGO_SETTINGS_MODULE", "day68_orm.settings") import django django.setup() from app01 import models # all 查询所有数据 ——》QuerySet ret = models.Person.objects.all() # print(ret) # get 获取一个对象 如果查询没有或者多个 就报错 ret = models.Person.objects.get(id=1) ret = models.Person.objects.get(name='和尚') # print(ret) # filter 查询所有满足条件的对象 ——》QuerySet ret = models.Person.objects.filter(id=1) ret = models.Person.objects.filter(name='杜举飞1') # exclude 查询所有不满足条件的对象 ——》QuerySet ret = models.Person.objects.exclude(id=1) # values 不写参数 取对象的所有字段数据 指定参数 取对象指定字段的参数 ——》QuerySet 元素是字典 ret = models.Person.objects.values('name','age') # print(ret) # print('*'*120) # for i in ret: # print(i,type(i)) # values_list # 不写参数 取对象的所有字段数据 元组形式 # 指定参数 取对象指定字段的参数 ——》QuerySet 按照你参数顺序排序 ret = models.Person.objects.values_list('age','name') # print(ret) # # print('*'*120) # for i in ret: # print(i,type(i)) # order_by 按照指定字段排序 默认升序 加负号降序 # 可以多字段排序 ret =models.Person.objects.all().order_by('age','-id') # for i in ret: # print(i,i.id,i.age) # reverse 对已经排序的QuerySet进行反向排序 # 用了order_by 要不用了ordering ret =models.Person.objects.all().order_by('age','-id').reverse() # for i in ret: # print(i,i.id,i.age) # ret = models.Person.objects.all() # print(ret) # ret = models.Person.objects.all().reverse() # print(ret) # distinct 去重 # count() 计数 对QuerySet的对象进行计数 ret = models.Person.objects.filter(id=100).count() # first 取QuerySet中的第一元素 ret = models.Person.objects.all().first() ret = models.Person.objects.last() # print(ret) ret = models.Person.objects.filter(id=100).exists() print(ret) """ 返回QuerySet的方法： 1. all() 2. filter() 3. exclude() 4. values() 5. values_list() 6. reverse() 7. distinct() 8. order_by() 返回具体对象的方法： 1. get() 2. first() 3. last() 返回数字的方法： 1. count() 返回布尔值： 1. exists() """
2双下划线
import os if __name__ == '__main__': os.environ.setdefault("DJANGO_SETTINGS_MODULE", "day68_orm.settings") import django django.setup() from app01 import models ret = models.Person.objects.filter(id__gt=1) ret = models.Person.objects.filter(id__lt=5) # less than ret = models.Person.objects.filter(id__gte=3) ret = models.Person.objects.filter(id__lte=3) ret = models.Person.objects.filter(id__gte=3,id__lte=5) ret = models.Person.objects.filter(id__in=[1,3,5,7,9,]) # in ret = models.Person.objects.exclude(id__in=[1,3,5,7,9,]) # not in ret = models.Person.objects.filter(name__contains='du') ret = models.Person.objects.filter(name__icontains='du') ret = models.Person.objects.filter(id__range=[1,5]) ret = models.Person.objects.filter(name__startswith='杜') ret = models.Person.objects.filter(name__endswith='飞') # ret = models.Person.objects.filter(birth__contains='2018-06') # ret = models.Person.objects.filter(birth__month=6) # ret = models.Person.objects.filter(birth__day=1) print(ret)
外键
import os if __name__ == '__main__': os.environ.setdefault("DJANGO_SETTINGS_MODULE", "day68_orm.settings") import django django.setup() from app01 import models # 正向查询 # 基于对象查询 # book_obj = models.Book.objects.filter(id=5).first() # print(book_obj.title) # print(book_obj.publisher) # print(book_obj.publisher.id) # print(book_obj.publisher.name) # 基于字段查询 # ret = models.Book.objects.filter(publisher__name='沙河出版社') ret = models.Book.objects.filter(publisher__id=1) # print(ret) # for i in ret: # print(i.publisher.name) # 反向查询 # 没有指定related_name，使用pub_obj.book_set.all() 拿所有出版社关联的书籍对象 # ret = models.Publisher.objects.get(id=1) # print(ret.book_set.all()) # 指定related_name = 'books'，使用pub_obj.books.all() 拿所有出版社关联的书籍对象 # print(ret.books.all()) # 基于字段查询 ret = models.Publisher.objects.filter(books__title='跟金老板学开车') print(ret)
多对多
import os if __name__ == '__main__': os.environ.setdefault("DJANGO_SETTINGS_MODULE", "day68_orm.settings") import django django.setup() from app01 import models author_obj = models.Author.objects.first() # print(author_obj.books.all()) # print(type(author_obj.books)) # author_obj.books.create(title='跟金老板学美容美发', publisher_id=1) # 1. 先创建书籍对象 # 2. 创建author_obj和新建书籍对象的对应关系 # shahe = models.Publisher.objects.first() # # shahe.books.create(title='跟金老板学烫头3') # author_obj.books.set([]) book_obj = models.Book.objects.first() # author_obj.books.clear() pub_obj = models.Publisher.objects.first() pub_obj.books.clear()
聚合和分组
import os if __name__ == '__main__': os.environ.setdefault("DJANGO_SETTINGS_MODULE", "day68_orm.settings") import django django.setup() from app01 import models from django.db.models import Avg, Sum, Max, Min, Count # ret = models.Book.objects.aggregate(Sum('price'),Count('id'),pingjun=Avg('price'),) # print(ret) # ret = models.Book.objects.annotate(Count('author'),).values() # for i in ret: # print(i) # ret = models.Publisher.objects.annotate(min_price=Min('books__price')).values() # for i in ret: # print(i) # ret = models.Book.objects.annotate(author_num=Count('author')).filter(author_num__gt=1) # for i in ret: # print(i) # # ret = models.Book.objects.annotate(author_num=Count("author")).order_by("-author_num") # print(ret) # ret = models.Author.objects.annotate(Sum('books__price')).values() print(ret)
F和Q
import os if __name__ == '__main__': os.environ.setdefault("DJANGO_SETTINGS_MODULE", "day68_orm.settings") import django django.setup() from app01 import models # ret = models.Book.objects.filter(id__gt=1) # print(ret) from django.db.models import F, Q # ret = models.Book.objects.filter(kucun__lt=F('sale')) # for i in ret: # print(i.title,i.kucun,i.sale) # book_obj = models.Book.objects.get(id=1) # book_obj.title= '跟金老板学开潜艇' # book_obj.save() # models.Book.objects.all().update(kucun=F('kucun')* 10) from django.db.models.functions import Concat from django.db.models import Value # models.Book.objects.all().update(title=F('title')+'(第一版)') # models.Book.objects.all().update(title=Concat(F('title'),Value('(第一版)'))) ret = models.Book.objects.filter(Q(id__lt=3) | Q(id__gt=5)) ret = models.Book.objects.filter(~Q(id=3), id__lt=5) print(ret)
事务
import os if __name__ == '__main__': os.environ.setdefault("DJANGO_SETTINGS_MODULE", "day68_orm.settings") import django django.setup() from app01 import models try: from django.db import transaction with transaction.atomic(): models.Publisher.objects.create(name='沙河银行') models.Publisher.objects.get(id=100) except Exception as e: print(str(e))