This is for the actual Schema branch (Sa 0.2 rev. 1468).
Using polymorphism as it is shown in the examples creates a SQL query like this : SELECT pjoin.info AS pjoin_info, pjoin.parent_id AS pjoin_parent_id, pjoin.type AS pjoin_type, pjoin.id AS pjoin_id FROM ( SELECT info.info AS info, contained.parent_id AS parent_id, contained.type AS type, info.id AS id FROM contained JOIN info ON contained.id = info.id UNION ALL SELECT NULL AS info, parent_id, type, id FROM ( SELECT contained.id AS id, contained.parent_id AS parent_id, contained.type AS type FROM contained WHERE contained.type = "contained" ) ) AS pjoin ORDER BY pjoin.id Everything works fine with SQLite. With MySQL this produces : SQLError: (OperationalError) (1248, 'Every derived table must have its own alias') Using an alias in the select of the UNION ALL solves the problem : SELECT pjoin.info AS pjoin_info, pjoin.parent_id AS pjoin_parent_id, pjoin.type AS pjoin_type, pjoin.id AS pjoin_id FROM ( SELECT info.info AS info, contained.parent_id AS parent_id, contained.type AS type, info.id AS id FROM contained JOIN info ON contained.id = info.id UNION ALL SELECT NULL AS info, pjoin_1.parent_id, pjoin_1.type, pjoin_1.id FROM ( SELECT contained.id AS id, contained.parent_id AS parent_id, contained.type AS type FROM contained WHERE contained.type = "contained" ) as pjoin_1 <---------------------------- ) AS pjoin ORDER BY pjoin.id Jürgen ------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Sqlalchemy-users mailing list Sqlalchemy-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users