1 Reply Latest reply: Nov 21, 2011 1:09 PM by mwickham RSS

    Composite Keys in ER Diagrammer

    901345
      Hi,

      I would like to know if its possible for the ER Diagrammer Tool in Oracle Designer to produce a Link Entity that has a composite key made up of three keys. To illustrate:

      I have 3 entities, COURSE, LECTURER, CENTRE

      A Course can be taught at more than Centre
      A Course can be taught by more than one Lecturer
      A Lecturer can teach courses(same or different course) at more than one Centre

      My normalization looks like this

      Course_Code, CourseName, {LecNo, LecName, CentreName}
      This will produce a Link Entity
      CourseSummary (_CourseCode, LecNo, CentreName_)

      How do I get the ER diagrammer to produce this table

      I know that once I establish a many to many relationship in the ERD tool it will auto produce the link entity with the appropriate composite key, however I cannot draw a many to many relationship between three entities. Can someone provide a solution other than manually drawing the link entity and establish the 1 to many relationships.