SLIDE

EXAMPLE 2: STUDENTS TAKING COURSES
SLIDE #9              RELATIONAL EXTENSION

Each relation is extended, to include data:

     
     Student relation:
     *****************
     -----------------------------------------
     | student  | age of | sex of |address of|
     | -------  | student|student | student  |
     -----------------------------------------
     | fred     | 19     | m      | florida  |
     | ann      | 23     | f      | georgia  |
     -----------------------------------------
     
     Course relation:
     ***************
     ---------------------------------
     | course  |  course  |class_room|
     | ------  |instructor| location |
     ---------------------------------
     | math    | joe      | A01      |
     | spanish | phil     | A07      |
     | history | tom      | A03      |
     ---------------------------------

     Grade relation:
     **************
     ------------------------------
     | student  | course  | grade |
     | -------  | ------  |       |
     ------------------------------
     | fred     | math    |  a    |
     | fred     | spanish |  c    |
     | ann      | history |  b    |
     ------------------------------