Tell me, I start correcting the database correctly:

While there are 3 tables: dbo.exam , dbo.offset , dbo.session .

exam and test similar structure: ID name date .

DBO.SESSION : ID fromdate Todate

session one, but it can have several tests and exams.

As I assume, I need to make a connection many to many .

so I do the following:

create table dbo.studentsession
(
  Sessionid int Foreign Key References DBO.Session (ID)
  Examid int Foreign Key References DBO.exam (ID),
  Offsetid Int Foreign Key References DBO.offset (ID)
  Constraint ID Primary Key (Sessionid, Examid, OffsetID)
)

p.s How can I refer to id dbo.studentsession from other tables?

Answer 1

If you claim that one session may contain multiple exams and tests , then these are two connections one to many .
More efficient to create tables Sessionexam sessionoffset , respectively, from Sessionid, Examid and SessionID, Offsetid . This will not make it possible to produce entries in the future table StudentSession . Accordingly, then from these tables on the external key sessionid you can get all the necessary information about the exams and tests by ID session.