查看原生sql

Teacher.objects.filter(fans__gte=500).order_by('nickname')

str(xxx.query)

字段双下划线，匹配条件

objects.get   返回模型列

filter 返回 query set

from django.shortcuts import render
from django.views.generic import View
from .models import *


def course_view(request):
   # 1.查询、检索、过滤
   teachers = Teacher.objects.all()
   print(teachers)  # 返回查询集
   # <QuerySet [<Teacher: Teacher object (holy)>, <Teacher: Teacher object (Jack)>, <Teacher: Teacher object (Allen)>]>

   teacher1 = Teacher.objects.get(nickname='Jack')  # 返回一条结果
   print(teacher1, type(teacher1))
   # Teacher object (Jack) <class 'course.models.Teacher'>

   teacher2 = Teacher.objects.filter(fans__gte=500)  # QuerySet 可以是多条结果
   for t in teacher2:
       print(f'讲师姓名{t.nickname}--粉丝数{t.fans}')
       # 讲师姓名Jack--粉丝数666
       # 讲师姓名Henry--粉丝数899

   # 2. 字段字符匹配，大小写敏感
   teacher3 = Teacher.objects.filter(fans__in=[666, 1200])
   print(teacher3)
   # <QuerySet [<Teacher: Teacher object (Jack)>]>

   teacher4 = Teacher.objects.filter(nickname__icontains='A')
   print(teacher4)
   # <QuerySet [<Teacher: Teacher object (Jack)>, <Teacher: Teacher object (Allen)>]>

   # 3.结果切片、排序、链式查询
   print(Teacher.objects.all()[:1])

   teacher5 = Teacher.objects.all().order_by('-fans')
   for teacher in teacher5:
       print(teacher.nickname, teacher.fans)
       # Henry 899
       # Jack 666
       # Allen 123
       # holy 0
   print(Teacher.objects.filter(fans__gte=500).order_by('nickname'))
   # <QuerySet [<Teacher: Teacher object (Henry)>, <Teacher: Teacher object (Jack)>]>

   # 4. 查看执行的原生SQL     str(xx.query)
   print(str(Teacher.objects.all().query))
   # SELECT "course_teacher"."nickname", "course_teacher"."introduction",
   #    "course_teacher"."fans", "course_teacher"."created_at", "course_teacher"."updated_at" FROM "course_teacher"

   return render(request, 'course.html')

query来显示原生的sql语句

查看原生的sql：

orm查询语句.query

query:  对xxx提出疑问

.all().order_by("xxx")  升序排列

.all().order_by("-xxx")  降序排列

get需要根据唯一键查询，返回一个对象，而不是QuertSet

filter 可输入查询条件（语法格式  属性__in/gte/exact/gt/it/lte/range）, 返回QuertSet

Meta中

ordering = ['pid']  根据pid字段排序

QuerySet 查询集 是一个可迭代的对象。

‘’‘’‘’‘看了看ik·

第六章！！！！

查询集介绍：

查询、检索、过滤

teacher = Teacher.objects.all()

teacher = Teacher.objects.get(主键、唯一键)返回一条结果

teacher = Teacher.objects.filter(fans__gte =) 返回多条结果 字段数据匹配大小写敏感 (fans__gte =大于等于、fans__exact刚好等于、fans__gt大于、fans__in在某某之内 、fans__isnull是否为空、fans__lt小于、fans__lte小于等于、fans__range在某某范围之内、、、、)

结果切片、排序、链式查询

Teacher.Object.all()[:1]

Teacher.Object.all().order_by('fans')/('-fans')

Teacher.Object.filter(fans__get).order_by('nickname')

查看执行的原生sql：

str(语句例如Teacher.Object.filter(fans__get).order_by('nickname').query)