cascading-deletes

问题 Is it possible to predict the operations that follow a DELETE CASCADE automatically? In my software I would like to give the user a warning with details about the data that would be deleted then. 回答1: You can make a copy of the database and put triggers on the after delete DELIMITER $$ CREATE TRIGGER ad_table1_each AFTER DELETE ON table1 FOR EACH ROW BEGIN INSERT INTO log VALUES (null /*autoinc id*/ , 'table1' /*tablename*/ , old.id /*tableid*/ , concat_ws(',',old.field1,old.field2 /*CSV's of

问题 I'm not sure exactly sure what the correct terminology is for my question so I'll just explain what I want to do. I have a directed graph and after I delete a node I want all independently related nodes to be removed as well. Here's an example: Say, I delete node '11', I want node '2' to be deleted as well(and in my own example, they'll be nodes under 2 that will now have to be deleted as well) because its not connected to the main graph anymore. Note, that node '9' or '10' should not be

问题 I have 3 tables names articles,comments,addresses. articles -> fields(id,title,body) comments -> fields(id,article_id,comment) addresses-> fields(id,article_id,address) and in my articles controller i have kept dependent=>true and also cascadeCallbacks=>true. First i tried with dependent => true,i dint work then added cascade, still it does not work. Below is my code. $this->hasMany('Comments', [ 'className' => 'Comments', 'dependent' => true, 'cascadeCallbacks' => true, ]); $this->hasOne(

问题 I've been trying to find the answer to this question here. Several people seem to ask similar things, but I don't get the answers. I have an EF entity with a bunch of child entities (one-to-many relationship). I want to be able to delete the "parent" entity and have all the child entities deleted at the same time. Some people mention "Cascade Delete" should be set on both EF model and database (Sql Server in my case). The problem is: I have absolutely no idea how to do this (seems to be

问题 I've a MySQL table "folders": CREATE TABLE IF NOT EXISTS `folders` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `folder_key` varchar(40) NOT NULL, `parent_key` varchar(40) NOT NULL, `name` varchar(16) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB; I don't use integer IDs, only keys (alphanumeric hashes, which I've replaced with words to make things more clear). So, folder_key & parent_key are SHA-1 hashes (in my real application). INSERT INTO `folders` (`id`, `folder_key`, `parent_key`,

问题 I implemented a bidirectional 1:1 relationship based on this answer: Primary /Foreign Key in Entity Framework I define the bidirectional relation this way: public class Student { public virtual int StudentId { get; set; } public virtual Anamnesis Anamnesis { get; set; } . . . } public class Anamnesis { [Key, ForeignKey("Student")] public int AnamnesisId { get; set; } public virtual Student Student { get; set; } . . . } where, Student is the principal entity and Anamnesis it the entity that

问题 I have 2 domain class with a many to many relationship. When I delete the entity that belongs to the other, I have to remove the relation before in order to avoid a foreign key error. I would like to put this code in the beforeDelete event, but I obtain a problem with optimistc locking. This is the code of the domain classes: class POI { static belongsTo = [Registration]; static hasMany = [registrations: Registration] def beforeDelete = { def poiId = this.id POI.withNewSession { session ->

问题 Sometimes I'm trying to delete just ONE row in MSSQL and I fall into countless deletes up the hierarchy because of references due to foreign-key constraints. Is there any quick way to automatically cascade-delete without having to setup the foreign-key constraints with cascade delete? It's just this one time that I need the cascade-delete... on-demand -- not always. Any chance? Any equivalents? 回答1: If you want a point and shoot dynamic sql solution, this uses a recursive query to build a

问题 I have two tables in an existing (MSSQL 2008 R2) database that are related by a link table. The two tables are "Plan" and "Tips". The link table is "PlanTipLinks". Plans can have many tips, and tips can be associated with multiple plans (i.e. it's a many-to-many relationship). In the application, I only care about the "Plan.Tips" relationship. I don't need the Tip.Plans inverse relationship. The foreign key references in the link table cannot be null. I'm using the following fluent API code

问题 I am trying to cascade delete rows in a join table via one of its foreign keys and it has another table related to it that I would like to remove all rows associated with this ID as well. So it looks like the diagram below. When I use Session.delete(reqCandObject) with hibernate it works fine and cascades through deleting the One entry from the candidate_jobReq table as well as the associated comments. However, I want to delete all of the candidate_jobReq entries that have a certain candidate