SQL

SLIDE #14          SELECTING DATA BETWEEN SEVERAL RELATIONS

To select data from several relations, we use the select command,
in conjunction with the from clause and the where commands.

                      select name, teacher
                      from student, course, grade
                      where student.name=grade.name
                      and grade.course_id=course.course_id;

The where clause specifies that we want:

. student name in the student relation and grade relation to be identical

. course_id in the course relation and grade relation to be identical

We edit a file, called sqlsession7  to select data from several relations.