Page 71 - Database-En-V3

4- The following one-to-many relationship appears as in the
picture:

• Many-to-Many relationship
In this type of relationship, a row in table A can have many
identical rows in table B, and vice versa. You can create this
relationship through a third table, or what is called the
intermediate table or connection table, whose primary key is
two foreign keys from both table A and table B.
o For example, the student data table, calculators, and the
study subjects table, have a many-to-many relationship
because a student can register more than one study
subject, and also the study subject can have more than
one student enter it.
o In order to create this relationship, you must create a
connection table, which is the students table with
academic subjects, then create a one-to-many
relationship between the computers students table and
the students with academic subjects, and create a second
one-to-many relationship between the academic subjects
table and the students table with academic subjects.

64 Training unit in the field of technological information - at the Supreme Council of Universities © Intellectual property rights 2024