用在where后:

　　　　Book.objects.filter(publisher_id="").extra(where=["title='python学习1'"])　　　　

　　用在select后　　

　　　　Book.objects.filter(publisher_id="").extra(select={"count":"select count(*) from hello_book"})

book = Book.objects.raw("select * from hello_book") #返回模型实例

　　　　for item in book:

　　　　　　print(item.title)

from django.db import connection

cursor = connection.cursor()

# 插入

cursor.execute("insert into hello_author(name) values('xiaol')")

# 更新

cursor.execute("update hello_author set name='xiaol' where id=1")

# 删除

cursor.execute("delete from hello_author where name='xiaol'")

# 查询

cursor.execute("select * from hello_author")

# 返回一行

raw = cursor.fetchone()

print(raw)

# 返回所有

# cursor.fetchall()