self-reference

I have a self-referential MySQL table with a recursive parent_id: CREATE TABLE `recursive` ( `id` int(11) NOT NULL auto_increment, `parent_id` int(11) default NULL, `name` varchar(100) NOT NULL, PRIMARY KEY (`id`), KEY `data_categorysource_parent_id` (`parent_id`), CONSTRAINT `parent_id_refs_id_627b4293` FOREIGN KEY (`parent_id`) REFERENCES `data_categorysource` (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 During testing, I want to empty it but TRUNCATE fails: TRUNCATE `recursive` /* SQL Error: Cannot delete or update a parent row: a foreign key constraint fails... I currently have to manually

I am trying to serialize a DefaultMutableTreeNode oject with jackson into a json string. Therefore i need to use a mix-in abstract class that is kind of a proxy to the DefaultMutableTreeNode class. This is probably because of self-reference fields but i am not able to recognize them. Mix-in class: @JsonIgnoreProperties(ignoreUnknown = true) public abstract class DefaultMutableTreeNodeMixIn { @JsonCreator public DefaultMutableTreeNodeMixIn(@JsonProperty Object userObject) {}; @JsonCreator public DefaultMutableTreeNodeMixIn(@JsonProperty Object userObject, @JsonProperty boolean allowsChildren) {

I have a "Job" table that contains jobs. The fact is Jobs are not always done in one go.. you can have a job that has many visits. I intended to represent that as another job but linked back to the original job via self referencing linkId. I am having trouble representing this using the fluent API. Its a one to many relationship.. one job might have many visits and thus a number of linkId's point back to the orginal job. The link Id would back to the orginal job Id. Its also optional since most jobs might be completed in one go.. I have looked for this but its difficult to turn the other

I am creating a linked list with self referential class in C++ and I want to have a static pointer of the type Item (Item is the class name) named "startPointer" so that when i call my static member function "free" , it can free up the memory by using Item::startPointer but i am getting an error(shown after code). Pls Help, class Item { public: std::string name; int row,column; int fileType; Item *ptr; static Item *startPointer; void setNextPointer(Item* ptr) { ptr=ptr; } Item *getNextPointer() { return ptr; } static void free() { Item *p,*temp; p=startPointer; while(p!=NULL) { temp=p; p=p-

Taking Ryan Bates' asciicast as an example: http://asciicasts.com/episodes/163-self-referential-association He ends with two associations of User :friends :inverse_friends Given that a user would not care who instigated the friendship, you would want a User association that was simply :friends that consisted of both relationships. i.e Relationships instigated by the user and relationships instigated by the user's friend. So how can you achieve this bidirectional self-referential association? UPDATE - Josh Susser has a post about this here: http://blog.hasmanythrough.com/2006/4/21/self

I'm writing a mentorship program for our church in rails (im still farily new to rails).. And i need to model this.. contact has_one :father, :class_name => "Contact" has_one :mother, :class_name => "Contact" has_many :children, :class_name => "Contact" has_many :siblings, :through <Mother and Father>, :source => :children So basically an objects "siblings" needs to map all the children from both the father and mother not including the object itself.. Is this possible? Thanks Daniel It's funny how questions that appear simple can have complex answers. In this case, implementing the reflexive