Django model select的各种用法详解

作者: Oscar_hailiang | 来源:发表于2019-05-22 17:52 被阅读0次

Django model select的各种用法详解
Django model select的各种用法详解
Django model select 各种查询
Django model update的各种用法介绍
django教程--model教程之查询高级用法
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Models#1

1. 基本操作

# 01 获取所有数据，对应SQL：select * from User
User.objects.all()
# 02 获取匹配数据，对应SQL：select * from User where name = '咖啡吧'
User.objects.filter(name='咖啡吧')
# 03 获取不匹配数据，对应SQL：select * from User where name != '咖啡吧'
User.objects.exclude(name='咖啡吧')
# 获取单条数据，对应SQL：select * from User where id = 125
User.objects.get(id=125)

2. 常用操作

# 获取总数，对应SQL：select count(1) from User
User.objects.count()
# 获取总数，对应SQL：select count(1) from User where name = '运维咖啡吧'
User.objects.filter(name='运维咖啡吧').count()
# 大于，>，对应SQL：select * from User where id > 724
User.objects.filter(id__gt=724)
# 大于等于，>=，对应SQL：select * from User where id >= 724
User.objects.filter(id__gte=724)
# 小于，<，对应SQL：select * from User where id < 724
User.objects.filter(id__lt=724)
# 小于等于，<=，对应SQL：select * from User where id <= 724
User.objects.filter(id__lte=724)
# 同时大于和小于， 1 < id < 10，对应SQL：select * from User where id > 1 and id < 10
User.objects.filter(id__gt=1, id__lt=10)
# 包含，in，对应SQL：select * from User where id in (11,22,33)
User.objects.filter(id__in=[11, 22, 33])
# 不包含，not in，对应SQL：select * from User where id not in (11,22,33)
User.objects.exclude(id__in=[11, 22, 33])
# 为空：isnull=True，对应SQL：select * from User where pub_date is null
User.objects.filter(pub_date__isnull=True)
# 不为空：isnull=False，对应SQL：select * from User where pub_date is not null
User.objects.filter(pub_date__isnull=True)
# 匹配，like，大小写敏感，对应SQL：select * from User where name like '%sre%'，SQL中大小写不敏感
User.objects.filter(name__contains="sre")
# 匹配，like，大小写不敏感，对应SQL：select * from User where name like '%sre%'，SQL中大小写不敏感
User.objects.filter(name__icontains="sre")
# 不匹配，大小写敏感，对应SQL：select * from User where name not like '%sre%'，SQL中大小写不敏感
User.objects.exclude(name__contains="sre")
# 不匹配，大小写不敏感，对应SQL：select * from User where name not like '%sre%'，SQL中大小写不敏感
User.objects.exclude(name__icontains="sre")
# 范围，between and，对应SQL：select * from User where id between 3 and 8
User.objects.filter(id__range=[3, 8])
# 以什么开头，大小写敏感，对应SQL：select * from User where name like 'sh%'，SQL中大小写不敏感
User.objects.filter(name__startswith='sre')
# 以什么开头，大小写不敏感，对应SQL：select * from User where name like 'sh%'，SQL中大小写不敏感
User.objects.filter(name__istartswith='sre')
# 以什么结尾，大小写敏感，对应SQL：select * from User where name like '%sre'，SQL中大小写不敏感
User.objects.filter(name__endswith='sre')
# 以什么结尾，大小写不敏感，对应SQL：select * from User where name like '%sre'，SQL中大小写不敏感
User.objects.filter(name__iendswith='sre')
# 排序，order by，正序，对应SQL：select * from User where name = '运维咖啡吧' order by id
User.objects.filter(name='运维咖啡吧').order_by('id')
# 多级排序，order by，先按name进行正序排列，如果name一致则再按照id倒叙排列
User.objects.filter(name='运维咖啡吧').order_by('name','-id')
# 排序，order by，倒序，对应SQL：select * from User where name = '运维咖啡吧' order by id desc
User.objects.filter(name='运维咖啡吧').order_by('-id')

3. 进阶操作

# limit，对应SQL：select * from User limit 3;
User.objects.all()[:3]
# limit，取第三条以后的数据，没有对应的SQL，类似的如：select * from User limit 3,10000000，从第3条开始取数据，取10000000条（10000000大于表中数据条数）
User.objects.all()[3:]
# offset，取出结果的第10-20条数据（不包含10，包含20）,也没有对应SQL，参考上边的SQL写法
User.objects.all()[10:20]
# 分组，group by，对应SQL：select username,count(1) from User group by username;
from django.db.models import Count
User.objects.values_list('username').annotate(Count('id'))
# 去重distinct，对应SQL：select distinct(username) from User
User.objects.values('username').distinct().count()
# filter多列、查询多列，对应SQL：select username,fullname from accounts_user
User.objects.values_list('username', 'fullname')
# filter单列、查询单列，正常values_list给出的结果是个列表，里边里边的每条数据对应一个元组，当只查询一列时，可以使用flat标签去掉元组，将每条数据的结果以字符串的形式存储在列表中，从而避免解析元组的麻烦
User.objects.values_list('username', flat=True)
# int字段取最大值、最小值、综合、平均数
from django.db.models import Sum,Count,Max,Min,Avg
User.objects.aggregate(Count(‘id’))
User.objects.aggregate(Sum(‘age’))

4. 时间字段

# 匹配日期，date
User.objects.filter(create_time__date=datetime.date(2018, 8, 1))
User.objects.filter(create_time__date__gt=datetime.date(2018, 8, 2))

# 匹配年，year
User.objects.filter(create_time__year=2018)
User.objects.filter(create_time__year__gte=2018)

# 匹配月，month
User.objects.filter(create_time__month__gt=7)
User.objects.filter(create_time__month__gte=7)

# 匹配日，day
User.objects.filter(create_time__day=8)
User.objects.filter(create_time__day__gte=8)

# 匹配周，week_day
User.objects.filter(create_time__week_day=2)
User.objects.filter(create_time__week_day__gte=2)

# 匹配时，hour
User.objects.filter(create_time__hour=9)
User.objects.filter(create_time__hour__gte=9)

# 匹配分，minute
User.objects.filter(create_time__minute=15)
User.objects.filter(create_time__minute_gt=15)

# 匹配秒，second
User.objects.filter(create_time__second=15)
User.objects.filter(create_time__second__gte=15)

# 按天统计归档
today = datetime.date.today()
select = {'day': connection.ops.date_trunc_sql('day', 'create_time')}
deploy_date_count = Task.objects.filter(
    create_time__range=(today - datetime.timedelta(days=7), today)
).extra(select=select).values('day').annotate(number=Count('id'))

5. Q 的使用

Q对象可以对关键字参数进行封装，从而更好的应用多个查询，可以组合&(and)、|(or)、~(not)操作符。
例如：

from django.db.models import Q
# 对应原生SQL语句 select * from User where role like 'sre_%' and (name='公众号' or name='运维咖啡吧')
User.objects.filter(
    Q(role__startswith='sre_'),
    Q(name='公众号') | Q(name='运维咖啡吧')
)

通常更多的时候我们用Q来做搜索逻辑，比如前台搜索框输入一个字符，后台去数据库中检索标题或内容中是否包含

_s = request.GET.get('search')

_t = Blog.objects.all()
if _s:
    _t = _t.filter(
        Q(title__icontains=_s) |
        Q(content__icontains=_s)
    )

return _t

参考：https://mp.weixin.qq.com/s/JVh4UnS2Tql9gUVaBSoGuA