Django 联表查询操作方法

class Singler(BaseModel):
    """ 歌手表模型 """
    name = models.CharField(max_length=50)
    first_letter = models.CharField(max_length=15, editable=False)
    # 设置上传位置
    portrait = models.ImageField(upload_to=upload_save_path)
    birthday = models.DateField(default=date.today,blank=True)
    height = models.IntegerField(default=0,blank=True)
    weight = models.IntegerField(default=0,blank=True)
    constellation = models.CharField(max_length=50)
    english_name = models.CharField(max_length=50,default='-')
    gender = models.IntegerField(choices=((0, '女'), (1, '男')),default=1)
    country_name = models.CharField(max_length=50,default='-')
    desc = models.TextField()
class Singe(BaseModel):
    """ 单曲表 """
    name = models.CharField(max_length=50)
    duration = models.IntegerField(editable=False, default=0)
    playnum = models.IntegerField(default=0, editable=False)
    path = models.FileField(upload_to=upload_save_path)
    lyric = models.FileField(upload_to=upload_save_path)
    # 设置与歌手表关联外键 一对多外键设置在多的模型中
    singler = models.ForeignKey("Singler",on_delete=models.CASCADE)
class Album(BaseModel):
    """ 专辑表 """
    name = models.CharField(max_length=50)
    cover = models.ImageField(upload_to=upload_save_path)
    desc = models.CharField(max_length=255)
    single_num = models.IntegerField(default=0,editable=False)
    langs = [
        ('国语', '国语'),
        ('普通话', '普通话'),
        ('英语', '英语'),
        ('日韩', '日韩')
    ]
    single_lang = models.CharField(max_length=50,choices=langs,)
    # 设置与歌手表关联外键 一对多
    singler = models.ForeignKey("Singler",on_delete=models.CASCADE)
    # 设置与单曲表关联外键 多对多
    Singe = models.ManyToManyField('Singe')

info = Singe.objects.filter(id=1).first()
print('单曲信息：', info)
article = info.singler
print('歌手信息:', article)

info = Singler.objects.filter(id=1).first()
print('歌手信息：', info)
song = info.singe_set.first()
print('一首单曲：', song)
songs = info.singe_set.all()
print('全部单曲：', songs)

singler = models.ForeignKey("Singler",
on_delete=models.CASCADE,related_name='singler_info')

info = Singler.objects.filter(id=1).first()
print('歌手信息：', info)
song = info.singler_info.first()
print('一首单曲：', song)
songs = info.singler_info.all()
print('全部单曲：', songs)

info = Singe.objects.filter(singler__name='周杰伦').first()
print('单曲信息：', info)
article = info.singler
print('歌手信息:', article)

info = Singler.objects.filter(singler_info__name='告白气球').first()
print('歌手信息：', info)
song = info.singler_info.first()
print('单曲信息:', song)

p = Singe.objects.select_related('getname').
values('id', 'name', 'duration', 'singler__name')
# # 查看SQL查询语句
print(p.query)
# 查看结果 为dict格式
print(p)

f = Singler.objects.select_related('getname').
values('id', 'name', 'getname__name')
# 查看SQL查询语句
print(f.query)
# 查看结果
print(f)
print('#'*100)
# 获取两个模型的数据，以模型Singler的singe_num大于1为查询条件
f = Singler.objects.select_related('getname').
filter(singe_num__gt=1).values('id', 'name', 'getname__name')
# 查看SQL查询语句
print(f.query)
# 获取查询结果集的首个元素的字段getname__name的值
print(f[0]['getname__name'])

# 设置与单曲表关联外键 多对多
Singe = models.ManyToManyField(
    'Singe',
    verbose_name='单曲',
    help_text='请选择单曲',
    related_name='singe_info'
)

s = Singe.objects.prefetch_related('singe_info').filter(name='告白气球').first()
print(s)
# # 根据外键字段singe获取当前数据的多对多或一对多关系
print(s.singe_info.all())
print('#'*100)
# 使用values_list获取联合查询数据
s = Singe.objects.prefetch_related('singe_info').filter(name='告白气球')\
    .values_list('id', 'name', 'singe_info__name')
# 查看sql
print(s.query)
# 查看结果
print(s)
# 输出专辑名
print(s[0][2])

s1 = Singe.objects.raw('select * from player_singe as s 
left join player_singler as a on s.singler_id = a.id')
print('查询结果')
print(s1)
for item in s1:
    print(item)

s = Singe.objects.raw('select * from player_singe as s left join 
player_singler as a on s.singler_id = a.id where s.name = "告白气球"')
print('查询结果')
print(s.query)
print(s)
print(s[0])

from django.db import connection
cursor = connection.cursor()
# 执行SQL语句
cursor.execute('select * from player_singe as s left join
 player_singler as a on s.singler_id = a.id')
# 读取第一行数据
print(cursor.fetchone())
# 读取所有数据
print(cursor.fetchall())