Hi John,
On 04/09/09 06:35, John Kaufmann wrote:
In Base's New Relationship pane (Tools -> Relationships), how is the
cascade direction determined? Take the classic 3-table example of
[Department - Employee - EmployeePix] with these relationships:
Department (1) - (n) Employee (each Department record links to
multiple Employee records)
Employee (1) - (1) EmployeePhoto (each Employee records links to
one EmployeePhoto record)
Between a Department and its Employees, there /might/ be a cascade
relationship - that is, if a Department is deleted, all of its
Employees are deleted - but that's typically not a concern. What /is/
a typical concern is that if an Employee is deleted, the linked
EmployeePhoto record is deleted - but not the other way around: One
might need to delete or change an EmployeePhoto without deleting or
changing the Employee. So there is a clear unidirectional cascade.
How does Base determine that direction?
That depends on the database you use. As Base itself doesn't care, the
database has the responsibility to do the right. I didn't tested what
the embedded hsqldb database do. But in the relation ships design you
can select what should happen on each side differently. So in your
example just define that when an employee is deleted than his photo
should be deleted as well and when only his photo is deleted the
employee stays untouched.
Ocke
PS: The best list for Base questions is [email protected] or
[email protected]
John
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