1. Djano 与 MySQL
Django清除数据表中的所有数据
# 异常方法
Book.objects.all().delete() # 对于大型数据集，可能会失效
Book.objects.raw(‘‘‘delete from book‘‘‘) # 也失效了
文档说明：
Note that delete() is the only QuerySet method that is not exposed on a Manager itself. This is a safety mechanism to prevent you from accidentally requesting Entry.objects.delete(), and deleting all the entries. If you do want to delete all the objects, then you have to explicitly request a complete query set:
#解决方案
book = Book.objects.all()
book.delete()
# 又是返回值的问题。。。。。
Django批量插入mysql数据库，怎么处理NAN值
报错提示：
MySQLdb.err.ProgrammingError: nan can not be used with MySQL
# 解决方案
data.fillna(value=0) # 用0填充
Django执行sql语句返回数据
data = Book.objects.raw(sql_)
注意：sql_语句中查询的列必须包含主键，data的类型为rawqueryset()