Django-02 views 条件查询

import random

from django.db.models import Max, Avg, F, Q
from django.http import HttpResponse
from django.shortcuts import render

# Create your views here.
# 视图函数
# 第一个参数request
from app.models import Student


def hello(request):
    return HttpResponse('hello django!')


def home(request):
    # render 其实调用的 HttpResponse
    return render(request, 'home.html')



# 添加学生
def addStudent(request):

    # 学生对象
    stu = Student()
    stu.s_name = '张' + str(random.randint(1,10000))
    stu.s_age = random.randint(10,50)
    stu.s_sex = '男'
    stu.s_score = random.randint(0,101)

    # 写入
    stu.save()

    return HttpResponse('添加学生成功: ' + stu.s_name)


# 获取所有学生
def getStudents(request):
    # all() 所有数据
    students = Student.objects.all()

    # filter() 过滤[按条件查询where]
    # filter(键=值)
    # students = Student.objects.filter(id=3)
    # 成绩 > 50
    # students = Student.objects.filter(s_score__gt=50)

    # 多个条件
    # filter(键=值,键=值...)
    # students = Student.objects.filter(s_score__gt=50).filter(s_age__lt=40)


    # pk  primary_key
    # id 默认主键   【pk和id是等价的】
    # students = Student.objects.exclude(pk__gt=10)

    # 排序
    # students = Student.objects.order_by('-s_score')


    # students = Student.objects.all()
    # print(students)

    # students = Student.objects.values()
    # print(students)


    # 包含
    # students = Student.objects.filter(s_name__contains='3')

    # 以xx开头
    # students = Student.objects.filter(s_name__startswith='王')

    # students = Student.objects.filter(s_name__endswith='0')



    # in
    # students = Student.objects.filter( pk__in=[1,3,5,7,9] )


    # 时间
    # students = Student.objects.filter( s_date__year=2018 )


    str = ''
    for student in students:
        str += '
 学号:%d     姓名:%s     年龄: %d     成绩:%d     
' % (student.id, student.s_name,student.s_age, student.s_score)

    return HttpResponse(str)


def getone(request):
    # stu = Student.objects.get(pk=3)
    # stu = Student.objects.get(s_score=0)
    # stu = Student.objects.get(s_score=-100)


    # students = Student.objects.filter(pk=1)
    students = Student.objects.filter(s_score=-100)
    # if students.count()>0:   # 有数据
    #     stu = students.first()
    # else:   # 无数据
    #     stu = '无数据'


    if students.exists():
        stu = students.first()
    else:   # 无数据
        stu = '无数据'


    return HttpResponse(stu)



def pagestu(request):
    # Student.objects.all()[x:y] ==>  (x.y]
    students = Student.objects.all()[1:3]

    return HttpResponse(students)


def agg(request):

    m_score = Student.objects.aggregate( Max('s_score') )
    print(m_score['s_score__max'])

    m_avg = Student.objects.aggregate( Avg('s_score') )
    print(m_avg)

    return HttpResponse('聚合函数')


def fobj(request):
    # 年龄 大于 分数
    students = Student.objects.filter(s_age__gt=F('s_score'))

    return HttpResponse(students)

def qobj(request):
    # and 操作
    # students = Student.objects.filter(s_age__gt=18).filter(s_score__gt=80)

    # students = Student.objects.filter( Q(s_age__gt=18) & Q(s_score__gt=80) )

    # students = Student.objects.filter( Q(pk=3) | Q(pk=5) | Q(pk=10) )

    students = Student.objects.filter( ~Q(pk__lt=5) )

    return HttpResponse(students)


def update(request):
    stu = Student.objects.get(pk=2)
    stu.s_name = '张二'
    stu.save()

    return HttpResponse('更新数据')


def delstu(request):
    stu = Student.objects.get(pk=4)
    stu.delete()

    return HttpResponse('删除数据')