We have a change history logging table named
‘ChangeHistory’ and would like several tables to have a to-many
relationship to it.
Student table has a to-many relationship to ChangeHistory
named ‘toStudentChangeHistory’
School table has a to-many relationship to ChangeHistory
named ‘toSchoolChangeHistory’
ChangeHistory includes an attribute named
‘foreignKeyId’ that will contain the primary key of the table that
points to it; ie studentId or schoolId. Thought I would also have a
ChangeHistory attribute named ‘changeHistoryType’ that would
distinguish the tables (value either ‘STUDENT’ or
‘SCHOOL’)
toStudentChangeHistory join would be:
Where Student.studentId =
ChangeHistory.foreignKeyId and
ChangeHistory.changeHistoryType = ‘STUDENT’
toSchoolChangeHistory join would be:
Where School.schoolId =
ChangeHistory.foreignKeyId and
ChangeHistory.changeHistoryType = ‘SCHOOL’
I can not figure out how to specify the changeHistoryType
part of the join in the EOModeler.
Thought of a few work-a-rounds, but would rather not add
additional attributes. For instance, could add the changeHistoryType to
both the Student and School tables. Just seems like there should be a
better way of doing this.
Thanks for your help.
JohnR