ORM查詢練習

django

orm

from django.db import models

# create your models here.
class
publisher
(models.model):
name = models.charfield(max_length=32)
city = models.charfield(max_length=32)
def__str__
(self):
return self.name
class
book
(models.model):
title = models.charfield(max_length=32)
publish_date = models.datefield(auto_now_add=true)
price = models.decimalfield(max_digits=5, decimal_places=2)
publisher = models.foreignkey(to="publisher")
def__str__
(self):
return self.title
class
author
(models.model):
name = models.charfield(max_length=32)
age = models.integerfield()
phone = models.integerfield()
books = models.manytomanyfield(to="book", related_name="authors")
detail = models.onetoonefield(to="authordetail")
def__str__
(self):
return self.name
class
authordetail
(models.model):
bobby = models.charfield(max_length=32)
addr = models.charfield(max_length=128)

import os

import sys
if __name__ == '__main__':
os.environ.setdefault("django_settings_module", "ormday70.settings")
import django
django.setup()
# 查詢所有書名裡包含沙河的書
ret = models.book.objects.filter(title__contains="沙河")
print(ret)
# 查詢所有出版日期是2023年的書
ret = models.book.objects.filter(publish_date__year=2018)
print(ret)
# 查詢**大於10元的書
ret = models.book.objects.filter(price__gt=10)
print(ret)
# 找到在沙河的出版社
ret = models.publisher.objects.filter(city="沙河")
print(ret)
# distinct
# 查所有書關聯的出版社
ret = models.book.objects.all().values_list("publisher__name")
print(ret)
# distinct去重
print(ret.distinct())
# 將所有的書按照**倒敘排序
# 預設排序
ret = models.book.objects.all().order_by("price")
print(ret)
# 倒序
print(ret.reverse())
# 同時，支援使用減號表示倒序排序
ret = models.book.objects.all().order_by("-price")
print(ret)
# 查詢書名是沙河異聞錄的書的出版社的city
ret = models.book.objects.filter(title="沙河異聞錄").values_list("publisher__city")
print(ret)
# 查詢書名是沙河異聞錄的書的作者的愛好（誇兩張表）
ret = models.book.objects.filter(title=
"沙河異聞錄"
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