Five years ago I was the recipient of an existing data model. It was designed with best intentions, but we've all learned a thing or two since then, and I've discovered there is a poor relationship between two of my tables.

I deal with students, so students are registered into classes and then there is attendance taken for those registrations. However, due to some issues I won't get into, the relationship between Registration and Attendance is non-existant.

So, I have a stu_id and cls_id column in both tables, but they can not be foreign keyed. Can I create this relationship in LLBLGen even though it does not exist in the database so that I can use my RegistrationEntity to pull my AttendanceCollection? I would want to join the stu_id and cls_id columns together. IF this is possible, does it then generate all the PrefetchPaths as well? (crossing my fingers)

NickD wrote:

Five years ago I was the recipient of an existing data model. It was designed with best intentions, but we've all learned a thing or two since then, and I've discovered there is a poor relationship between two of my tables.

I deal with students, so students are registered into classes and then there is attendance taken for those registrations. However, due to some issues I won't get into, the relationship between Registration and Attendance is non-existant.

So, I have a stu_id and cls_id column in both tables, but they can not be foreign keyed. Can I create this relationship in LLBLGen even though it does not exist in the database so that I can use my RegistrationEntity to pull my AttendanceCollection? I would want to join the stu_id and cls_id columns together. IF this is possible, does it then generate all the PrefetchPaths as well? (crossing my fingers)

Assuming there is no logical reason the two fields cannot/should not be related (different data types, non-unique data on the PK side, etc) the designer can create "Custom Relations" on any two fields that fit the criteria. See the documentation "Using the Designer::Adding custom relations" for more information.

Jeff...

I've had great success in doing just that, creating relationships in the LLBLGen GUI where no relationship exists. I'm then able to use it exactly as though it were a real relationship, including using the Core.Manager templates (sweet...).

Be sure what ordinarily would have been the PK and FK are of the same datatype. If they aren't, I don't think it can be done.

Thanks guys. I'll give that a try!

Thanks for helping out, guys

The custom relations feature has been added just for this: when there is no FK present in the database, you still can add relations and use the full power of the generated code. (and because I wanted to support MySql and MySql has FK's but I couldn't read them, I had to add this feature )

Otis wrote:

Thanks for helping out, guys

The custom relations feature has been added just for this: when there is no FK present in the database, you still can add relations and use the full power of the generated code. (and because I wanted to support MySql and MySql has FK's but I couldn't read them, I had to add this feature )

Wonderful! Just the answer I was looking for.