Python-django's ORM

• class represents a database table
• The object of the class refers to a row of records in the database
• The FK field refers to a row of data in the associated table
• Manytomany field, automatically generates the third table: Dependency table indirect operation on third table
• Forward: FK field; reverse: Lowercase class name) _set =>releated_name= ' ssss '
• Who is the main table? All of its data is listed
• Models. Student.object.all (). VALUES (' Useename ', ' cs__title ')
• Models. Classes.object.all (). VALUES (' tittle ', ' ssss__username

Example:
-Names of all students and their class names, QuerySet
Stu_list = Student.objects.all ()
SELECT * from TB;
[Obj,obj,obj,obj]

Stu_list = Student.objects.all (). VALUES ("id", ' username ')
Select Id,username from TB;
[{"id": 1, ' username ': ' xx '},{id: ', Username: '}]

Stu_list = Student.objects.all (). Values_list ("id", ' username ')
[(1, ' Root '), (2, ' Alex ')]


Stu_list = Student.objects.all (). VALUES (' username ', ' cs__name ')
For row in Stu_list:
Print (row[' username '],row[' cs__name ')

Stu_list = Student.objects.all (). VALUES (' username ', "cs__titile", "Cs__fk__name")

Python-django's ORM