one-to-many

Ok so this is probably a trivial question but I'm having trouble visualizing and understanding the differences and when to use each. I'm also a little unclear as to how concepts like uni-directional and bi-directional mappings affect the one-to-many/many-to-many relationships. I'm using Hibernate right now so any explanation that's ORM related will be helpful. As an example let's say I have the following set-up: public class Person{ private Long personId; private Set<Skill> skills; //Getters and setters } public class Skill{ private Long skillId; private String skillName; //Getters and setters

I'm trying to use the @OrderColumn annotation with Hibernate 3.5 @OneToMany(mappedBy = "parent",fetch=FetchType.EAGER, cascade=CascadeType.ALL) @OrderColumn(name = "pos") private List<Children> childrenCollection; When retrieving data, everything works fine. But I can't make it reorder elements in the List and save the new order to the database. The combination of @OneToMany(mappedBy="...") and @OrderColumn is not supported by Hibernate. This JIRA issue tracks a request to throw a more obvious error message when this invalid combination is used: http://opensource.atlassian.com/projects

I'm looking for a solution to manage a one-to-many relation within an HTML form using jQuery . I'm developing with Spring , Spring MVC and Hibernate . I found many tracks on the web, but not any working full-example. The background I've three JPA entities: Consult.java (1) @Entity @Table(name = "consult") public class Consult private Integer id; private String label; private Set<ConsultTechno> consultTechnos; /* getters & setters */ } ConsultTechno.java (2) @Entity @Table(name = "consult_techno") public class ConsultTechno { private Integer id; private Techno techno; private Consult consult;

I need something similar to these 2 SO questions, but using Informix SQL syntax. Concatenate several fields into one with SQL SQL Help: Select statement Concatenate a One to Many relationship My data coming in looks like this: id codes 63592 PELL 58640 SUBL 58640 USBL 73571 PELL 73571 USBL 73571 SUBL I want to see it come back like this: id codes 63592 PELL 58640 SUBL, USBL 73571 PELL, USBL, SUBL See also group_concat() in Informix . I believe that the answer you need is a user-defined aggregate, similar to this one: CREATE FUNCTION gc_init(dummy VARCHAR(255)) RETURNING LVARCHAR; RETURN '';