After doing more reading, this only relates to multiple class inheritance, which is useful anytime you want two or more classes to relate to the same record return from the database, is that an accurate summary?
I'm trying to get of "real-life" feel for which situations would benefit from multiple class inheritance so I can spot them if they present themselves. Any input for me or other readers at a general level? On Apr 1, 8:26 pm, Michael Bayer <mike...@zzzcomputing.com> wrote: > On Apr 1, 2010, at 8:22 PM, Kent wrote: > > > What is the difference between: > > > session.query(Employee).join([Engineer, Manager]).\ > > filter(or_(Engineer.engineer_info=='w', > > Manager.manager_data=='q')) > > > and > > > session.query(Employee).with_polymorphic([Engineer, Manager]).\ > > filter(or_(Engineer.engineer_info=='w', > > Manager.manager_data=='q')) > > the join to Engineer is going to create "select * from employees join (select > * from employees join engineer ...) on ..." not what you want. this is > another thing I covered at the tutorial this year. If OTOH you join to > Engineer.__table__ and Manager.__table__, you'll get what you want > (with_polymorphic is a convenience feature at this piont and not very > flexible). > > > > > ? > > > -- > > You received this message because you are subscribed to the Google Groups > > "sqlalchemy" group. > > To post to this group, send email to sqlalch...@googlegroups.com. > > To unsubscribe from this group, send email to > > sqlalchemy+unsubscr...@googlegroups.com. > > For more options, visit this group > > athttp://groups.google.com/group/sqlalchemy?hl=en. > > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
