ORM中基于对象查询与基于queryset查询
感谢老男孩~ 一步一步走下去
前面是视图函数 后面是表结构models.py
from django.shortcuts import render, HttpResponse from django.http import JsonResponse # Create your views here. from app01 import models def query(request): #########基于对象查询(子查询)########### # 一对多 book(publish forkey) ---> publish 正向查询 # 正向查询 按字段 # 反向查询 表名_set.all() 一对多 # 查询python这本书籍的出版社的邮箱 python = models.Book.objects.filter(title="python").first() # 对象 print(python.publish.email) # 查询苹果出版社出版的书籍名称 (反向查询 表名小写_set.all()) # publish_obj = models.Publish.objects.filter(name="苹果出版社").first() #对象 # print(publish_obj) # for obj in publish_obj.book_set.all(): # print(obj.title) # 按字段(author.all()) # 多对多 book ---------> author # <--------- # book_set.all() # 正向查询 # 查询python的作者的年龄 # python = models.Book.objects.filter(title="python").first() # for author in python.authors.all(): # print(author.name,author.age) # 反向查询 # 查询alex出版过的书籍名称 # alex = models.Author.objects.filter(name="alex").first() # for book in alex.book_set.all(): # print(book.title) # 一对一 按字段authorDetail # author -----------> authordetail # <------------ # 按表名 author # 查询alex的手机号 (正向查询) # alex = models.Author.objects.filter(name="alex").first() # print(alex.authorDetail.telephone) # 查询家在北京的作者名字 (反向查询) # obj = models.AuthorDetail.objects.filter(addr="北京").first() # print(obj.author.name) print("分割线:", "*" * 100) # 如果addr为北京的人很多 执行了若干次的一对一执行 # obj_list = models.AuthorDetail.objects.filter(addr="北京").all() # for first in obj_list: # print(first.author.name) """ 查询python这本书籍的出版社的邮箱 models.book.objects.filter(title="python").first().publish.email 第一步: SELECT "app01_book"."nid", "app01_book"."title", "app01_book"."publishDate", "app01_book"."price ", "app01_book"."publish_id" FROM "app01_book" WHERE "app01_book"."title" = 'python' ORDER BY "app01_boo k"."nid" ASC LIMIT 1; args=('python',) 第二步:SELECT "app01_publish"."nid", "app01_publish"."name", "app01_publish"."city", "app01_publish"."e mail" FROM "app01_publish" WHERE "app01_publish"."nid" = 1; args=(1,) 即: #若干条子查询 select语句 select publish_id from Book where title = "python" select email from Publish where nid = 1 查询alex手机号 models.author.objects.filter(name="alex").first().authorDetail.telephone select authorDetail_id from author where name = "alex" select telephone from authordetail where nid = 1 """ #########基于queryset和__查询 (join)########### # 正向查询:按字段__ # 反向查询:表名小写__ """ 查询python 这本书籍的出版社的邮箱 select publish.email from Book left join Publish on book.publish_id = publish.nid where book.title = "python" """ # 查询python 这本书籍的出版社的邮箱 (正向查询) ret = models.Book.objects.filter(title="python").values("publish__email") #方式2 models.Publish.objects.filter(book__title="python").values("email") print(ret.query) # ret.query属性 就不需要在setging设置全局了 """ SELECT "app01_publish"."email" FROM "app01_book" INNER JOIN "app01_publish" ON ("app01_book"."publish_id" = "app01_publish"."nid") WHERE "ap p01_book"."title" = python """ #查询苹果出版社的书籍名称 #方式1 book = models.Publish.objects.filter(name="天空出版社").values("book__title") print(book.query) #方式2 book = models.Book.objects.filter(publish__name="天空出版社").values("title") print(book.query) """ SELECT "app01_book"."title" FROM "app01_publish" LEFT OUTER JOIN "app01_book" ON ("app01_publish"."nid" = "app01_book"."publish_id") WHERE "app01_publish"."name" = 天空出版社 SELECT "app01_book"."title" FROM "app01_publish" LEFT OUTER JOIN "app01_book" ON ("app01_book"."publish_id" = "app01_publish"."nid") WHERE "app01_publish"."name" = 天空出版社 """ #查询alex的手机号 alex = models.Author.objects.filter(name="alex").values("authorDetail__telephone") print(alex) alex = list(alex) print(alex) tel = models.AuthorDetail.objects.filter(author__name="alex").values("telephone") print(tel) #查询手机号以151开头的作者出版过的书籍名称以及对应的出版社名称 (五张表) book_ret = models.Book.objects.filter(authors__authorDetail__telephone__startswith="151").values("title","publish__name") print(book_ret) publish_ret = models.Publish.objects.filter(book__authors__authorDetail__telephone__startswith="151").values("book__title","name") print(publish_ret) """ SELECT "app01_book"."titl e", "app01_publish"."name" FROM "app01_book" INNER JOIN "app01_book_authors" ON ("app01_book"."nid" = "app01_book_authors"."book_id") INNER JOIN "app01_author" ON ("app01_book_authors"."author_id" = "app01_author"."nid") INNER JOIN "app01_authordetail" ON ("app01_author"."authorD etail_id" = "app01_authordetail"."nid") INNER JOIN "app01_publish" ON ("app01_book"."publish_id" = "app01_publish"."nid") WHERE "app01_autho rdetail"."telephone" LIKE 151% ESCAPE '\' """ # test查询手机号以151开头的作者出版过的书籍名称以及对应的出版社名称 (五张表) book = models.Book.objects.filter(authors__authorDetail__telephone__startswith="151").values("title","publish__name") publish = models.Publish.objects.filter(book__authors__authorDetail__telephone__startswith="151").values("book__title","name") print("this is test",book,publish) ###############################聚合与分组##################################### #查询所有书籍的价格和 from django.db.models import Sum, Count, Avg ret = models.Book.objects.all().aggregate(price_sum = Sum("price")) print(ret) #ret为字典 {'price_sum': Decimal('710.00')} #查询所有作者的平均年龄 ret = models.Author.objects.all().aggregate(age_avg = Avg("age")) print(ret) #统计有多少个作者 ret = models.Author.objects.all().aggregate(num = Count("nid")) print(ret) #分组 """ sql分组 emp表 id name age dep 1 alex 21 技术部 2 egon 23 技术部 3 wenzhou 25 运营部 4 jc 22 运营部 查询每一个部门的人数 sql: select Count(id) from emp group by dep orm: models.emp.objects.values("dep").annotate(c=Count("id")) emp表 id name age dep_id 1 alex 21 1 2 egon 23 2 3 wenzhou 25 2 dep表 id name 1 技术部 2 运营部 查询每一个部门名称以及对应人数 sql: select * from emp inner join dep on emp.dep_id = dep.id id name age dep_id dep.id dep.name 1 alex 21 1 1 技术部 2 egon 23 2 2 运营部 3 wenzhou 25 2 2 运营部 select dep.name, Count(*) from emp inner join dep on emp.dep_id = dep.id group by dep.id, dep.name ORM: 关键点: 1.queryset数据可以调用annotate() 2.annotate进行分组统计，按照前面的select的字段进行group by 3.annotate()返回值依然是queryset对象， 增加了分组统计的键值对 models.dep.objects.values("name").annotate(c=Count("emp__name")).values("name","c") models.emp.objects.values("dep__name").annotate(c=Count("name")).values("dep__name", "c") select dep.name, Count(emp.name) as c from dep inner join emp on .. group by dep.name select ___ from ___ inner join ___ on ... group by ___ """ ret = models.Publish.objects.values("name") #SELECT "app01_publish"."name" FROM "app01_publish" print(ret.query) from django.db.models import Max #查询每一个作者的名字以及出版过的书籍最高价格 ret = models.Author.objects.values("name").annotate(max_price = Max("book__price")).values("name","max_price") print(ret) """ select author.name, Max(book.price) as max_price from author inner join book_authors on ... inner join book on ... group by author.name """ #查询每一个出版社出版过的书籍的平均价格 ret = models.Publish.objects.values("name").annotate(avg_price = Avg("book__price")).values("name","avg_price") print(ret) #查询每一本书籍的作者个数 ret = models.Book.objects.values("title").annotate(author_count = Count("authors__name")).values("title","author_count") #或者将authors__name换成authors print(ret) #查询每一个分类的名称以及对应的文章数 # models.Category.objects.all().annotate(c = Count("article__title")).values("title","c") #统计不止2个作者的图书名称: 作者数大于两个 难点 #先统计每个本书籍的作者个数 ret = models.Book.objects.values("title").annotate(count=Count("authors__name")).values("title","count") print(ret) """ select book.title, Count(author.name) as c from book inner join book-authors on .. inner join author on .. group by book.id having c > 2 """ ret = models.Book.objects.values("title").annotate(count=Count("authors__name")).filter(count__gt=1).values("title","count") print(ret) #统计作者为2的图书名称 ret = models.Book.objects.values("title").annotate(count=Count("authors__name")).filter(count=2).values("title","count") print(ret) #统计出版的每一本价格大于100的书籍 ret = models.Book.objects.values("title").filter(price__gt=100).values("title","price") print(ret) #统计每一个出版出版的书籍及价格 ret = models.Publish.objects.values("name").annotate(count=Count("book__title")).values("name","book__title") print(ret) #统计每一个出版社出版的书籍个数 ret = models.Publish.objects.values("name").annotate(count=Count("book__title")).values("name","count") print(ret) #统计每一个出版社出版大于100的书籍名称 ret = models.Publish.objects.values("name").annotate().filter(book__price__gt=100).values("name","book__title","book__price") print(ret) return HttpResponse("ok")
from django.db import models # Create your models here. from django.db import models # Create your models here. class Author(models.Model): nid = models.AutoField(primary_key=True) name=models.CharField( max_length=32) age=models.IntegerField() # 与AuthorDetail建立一对一的关系 authorDetail=models.OneToOneField(to="AuthorDetail",on_delete=models.CASCADE) class AuthorDetail(models.Model): nid = models.AutoField(primary_key=True) birthday=models.DateField() telephone=models.BigIntegerField() addr=models.CharField( max_length=64) class Publish(models.Model): nid = models.AutoField(primary_key=True) name=models.CharField( max_length=32) city=models.CharField( max_length=32) email=models.EmailField() class Book(models.Model): nid = models.AutoField(primary_key=True) title = models.CharField( max_length=32) publishDate=models.DateField() price=models.DecimalField(max_digits=5,decimal_places=2) publish=models.ForeignKey(to="Publish",to_field="nid",on_delete=models.CASCADE) authors=models.ManyToManyField(to='Author',) #多对多关联字段
from django.shortcuts import render, HttpResponse
from django.http import JsonResponse
# Create your views here.
from app01 import models
def query(request):
#########基于对象查询(子查询)###########
# 一对多 book(publish forkey) ---> publish 正向查询
# 正向查询 按字段
# 反向查询 表名_set.all() 一对多
# 查询python这本书籍的出版社的邮箱
python = models.Book.objects.filter(title="python").first() # 对象
print(python.publish.email)
# 查询苹果出版社出版的书籍名称 (反向查询 表名小写_set.all())
# publish_obj = models.Publish.objects.filter(name="苹果出版社").first() #对象
# print(publish_obj)
# for obj in publish_obj.book_set.all():
# print(obj.title)
# 按字段(author.all())
# 多对多 book ---------> author
# <---------
# book_set.all()
# 正向查询
# 查询python的作者的年龄
# python = models.Book.objects.filter(title="python").first()
# for author in python.authors.all():
# print(author.name,author.age)
# 反向查询
# 查询alex出版过的书籍名称
# alex = models.Author.objects.filter(name="alex").first()
# for book in alex.book_set.all():
# print(book.title)
# 一对一 按字段authorDetail
# author -----------> authordetail
# <------------
# 按表名 author
# 查询alex的手机号 (正向查询)
# alex = models.Author.objects.filter(name="alex").first()
# print(alex.authorDetail.telephone)
# 查询家在北京的作者名字 (反向查询)
# obj = models.AuthorDetail.objects.filter(addr="北京").first()
# print(obj.author.name)
print("分割线:", "*" * 100)
# 如果addr为北京的人很多 执行了若干次的一对一执行
# obj_list = models.AuthorDetail.objects.filter(addr="北京").all()
# for first in obj_list:
# print(first.author.name)
"""
查询python这本书籍的出版社的邮箱 models.book.objects.filter(title="python").first().publish.email
第一步: SELECT "app01_book"."nid", "app01_book"."title", "app01_book"."publishDate", "app01_book"."price
", "app01_book"."publish_id" FROM "app01_book" WHERE "app01_book"."title" = 'python' ORDER BY "app01_boo
k"."nid" ASC LIMIT 1; args=('python',)
第二步:SELECT "app01_publish"."nid", "app01_publish"."name", "app01_publish"."city", "app01_publish"."e
mail" FROM "app01_publish" WHERE "app01_publish"."nid" = 1; args=(1,)
即: #若干条子查询 select语句
select publish_id from Book where title = "python"
select email from Publish where nid = 1
查询alex手机号 models.author.objects.filter(name="alex").first().authorDetail.telephone
select authorDetail_id from author where name = "alex"
select telephone from authordetail where nid = 1
"""
#########基于queryset和__查询 (join)###########
# 正向查询:按字段__
# 反向查询:表名小写__
"""
查询python 这本书籍的出版社的邮箱
select publish.email from Book left join Publish on book.publish_id = publish.nid where book.title = "python"
"""
# 查询python 这本书籍的出版社的邮箱 (正向查询)
ret = models.Book.objects.filter(title="python").values("publish__email")
#方式2
models.Publish.objects.filter(book__title="python").values("email")
print(ret.query) # ret.query属性 就不需要在setging设置全局了
"""
SELECT "app01_publish"."email" FROM "app01_book" INNER JOIN "app01_publish" ON ("app01_book"."publish_id" = "app01_publish"."nid") WHERE "ap
p01_book"."title" = python
"""
#查询苹果出版社的书籍名称
#方式1
book = models.Publish.objects.filter(name="苹果出版社").values("book__title")
print(book.query)
#方式2
book = models.Book.objects.filter(publish__name="苹果出版社").values("title")
print(book.query)
"""
SELECT "app01_book"."title" FROM "app01_publish"
LEFT OUTER JOIN "app01_book" ON ("app01_publish"."nid" = "app01_book"."publish_id")
WHERE "app01_publish"."name" = 苹果出版社
SELECT "app01_book"."title" FROM "app01_publish"
LEFT OUTER JOIN "app01_book" ON ("app01_book"."publish_id" = "app01_publish"."nid")
WHERE "app01_publish"."name" = 苹果出版社
"""
#查询alex的手机号
alex = models.Author.objects.filter(name="alex").values("authorDetail__telephone")
print(alex)
alex = list(alex)
print(alex)
tel = models.AuthorDetail.objects.filter(author__name="alex").values("telephone")
print(tel)
#查询手机号以151开头的作者出版过的书籍名称以及对应的出版社名称 (五张表)
book_ret = models.Book.objects.filter(authors__authorDetail__telephone__startswith="151").values("title","publish__name")
print(book_ret)
publish_ret = models.Publish.objects.filter(book__authors__authorDetail__telephone__startswith="151").values("book__title","name")
print(publish_ret)
"""
SELECT "app01_book"."titl
e", "app01_publish"."name" FROM "app01_book" INNER JOIN "app01_book_authors" ON ("app01_book"."nid" = "app01_book_authors"."book_id") INNER
JOIN "app01_author" ON ("app01_book_authors"."author_id" = "app01_author"."nid") INNER JOIN "app01_authordetail" ON ("app01_author"."authorD
etail_id" = "app01_authordetail"."nid") INNER JOIN "app01_publish" ON ("app01_book"."publish_id" = "app01_publish"."nid") WHERE "app01_autho
rdetail"."telephone" LIKE 151% ESCAPE '\'
"""
# test查询手机号以151开头的作者出版过的书籍名称以及对应的出版社名称 (五张表)
book = models.Book.objects.filter(authors__authorDetail__telephone__startswith="151").values("title","publish__name")
publish = models.Publish.objects.filter(book__authors__authorDetail__telephone__startswith="151").values("book__title","name")
print("this is test",book,publish)
###############################聚合与分组#####################################
#查询所有书籍的价格和
from django.db.models import Sum, Count, Avg
ret = models.Book.objects.all().aggregate(price_sum = Sum("price"))
print(ret) #ret为字典 {'price_sum': Decimal('710.00')}
#查询所有作者的平均年龄
ret = models.Author.objects.all().aggregate(age_avg = Avg("age"))
print(ret)
#统计有多少个作者
ret = models.Author.objects.all().aggregate(num = Count("nid"))
print(ret)
#分组
"""
sql分组
emp表
id name age dep
1 alex 21 保安部
2 egon 23 保安部
3 wenzhou 25 保安部
4 jc 22 保安部
查询每一个部门的人数
sql:
select Count(id) from emp group by dep
orm:
models.emp.objects.values("dep").annotate(c=Count("id"))
emp表
id name age dep_id
1 alex 21 1
2 egon 23 2
3 wenzhou 25 2
dep表
id name
1 保安部
2 保洁部
查询每一个部门名称以及对应人数
sql:
select * from emp inner join dep on emp.dep_id = dep.id
id name age dep_id dep.id dep.name
1 alex 21 1 1 保安部
2 egon 23 2 2 保洁部
3 wenzhou 25 2 2 保洁部
select dep.name, Count(*) from emp inner join dep on emp.dep_id = dep.id group by dep.id, dep.name
ORM:
关键点:
1.queryset数据可以调用annotate()
2.annotate进行分组统计，按照前面的select的字段进行group by
3.annotate()返回值依然是queryset对象， 增加了分组统计的键值对
models.dep.objects.values("name").annotate(c=Count("emp__name")).values("name","c")
models.emp.objects.values("dep__name").annotate(c=Count("name")).values("dep__name", "c")
select dep.name, Count(emp.name) as c from dep inner join emp on .. group by dep.name
select ___ from ___ inner join ___ on ... group by ___
"""
ret = models.Publish.objects.values("name") #SELECT "app01_publish"."name" FROM "app01_publish"
print(ret.query)
from django.db.models import Max
#查询每一个作者的名字以及出版过的书籍最高价格
ret = models.Author.objects.values("name").annotate(max_price = Max("book__price")).values("name","max_price")
print(ret)
"""
select author.name, Max(book.price) as max_price from author inner join book_authors on ...
inner join book on ...
group by author.name
"""
#查询每一个出版社出版过的书籍的平均价格
ret = models.Publish.objects.values("name").annotate(avg_price = Avg("book__price")).values("name","avg_price")
print(ret)
#查询每一本书籍的作者个数
ret = models.Book.objects.values("title").annotate(author_count = Count("authors__name")).values("title","author_count") #或者将authors__name换成authors
print(ret)
#查询每一个分类的名称以及对应的文章数
# models.Category.objects.all().annotate(c = Count("article__title")).values("title","c")
#统计不止2个作者的图书名称: 作者数大于两个 难点
#先统计每个本书籍的作者个数
ret = models.Book.objects.values("title").annotate(count=Count("authors__name")).values("title","count")
print(ret)
"""
select book.title, Count(author.name) as c from book inner join book-authors on ..
inner join author on ..
group by book.id having c > 2
"""
ret = models.Book.objects.values("title").annotate(count=Count("authors__name")).filter(count__gt=1).values("title","count")
print(ret)
#统计作者为2的图书名称
ret = models.Book.objects.values("title").annotate(count=Count("authors__name")).filter(count=2).values("title","count")
print(ret)
#统计出版的每一本价格大于100的书籍
ret = models.Book.objects.values("title").filter(price__gt=100).values("title","price")
print(ret)
#统计每一个出版出版的书籍及价格
ret = models.Publish.objects.values("name").annotate(count=Count("book__title")).values("name","book__title")
print(ret)
#统计每一个出版社出版的书籍个数
ret = models.Publish.objects.values("name").annotate(count=Count("book__title")).values("name","count")
print(ret)
#统计每一个出版社出版大于100的书籍名称
ret = models.Publish.objects.values("name").annotate().filter(book__price__gt=100).values("name","book__title","book__price")
print(ret)
return HttpResponse("ok")
原谅我这一生不羁放纵爱自由
