many to many and different requests - Strange behavior?

I am seeing unexpected strange behaviour.

I have two tables: student and study_class which have many to many
relationship.

1. when user A (student a) logs in, in run time he does,

student_a.study_classs = [class_physics] #in DB, this student does
not have class_physics

#does not Save.

2. User B logs into separate browser.

Student.objects.get(Study_class__exact = class_physics)

It returns "student_a" as one of the students even though student_a
above never saved.

3. User A logs out without saving. User B again does
Student.objects.get(study_class__exact = class_physics). This time
student_a is not returned.

Why this happening? (I use wsgi with django 1.1.1 and python 2.5 on
apache.)

--
You received this message because you are subscribed to the Google Groups "Django users" group.
To post to this group, send email to django-users@googlegroups.com.
To unsubscribe from this group, send email to django-users+unsubscribe@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/django-users?hl=en.