Cascade

问题 i have 2 class. Parent and child. as follows: @Entity @Table(name = "parent") public class Parent implements Serializable { private String name; private List<Child> childs; @OneToMany(mappedBy="parent") @Cascade({CascadeType.SAVE_UPDATE, CascadeType.DELETE}) public List<Child> getChilds() { return childs; } @Id @Column(name="parent_name") public String getName() { return name; } } > @Entity @Table(name = "child") public class Child implements Serializable { @JoinColumn(name="parent_name")

问题 Table SUBCOURSE references COURSE COURSE(id, name) SUBCOURSE(id, course_id, name) So, 1:M. Hibernate generates for Course: @OneToMany(fetch = FetchType.LAZY, mappedBy = "course", cascade = CascadeType.ALL) public Set getSubCourses() { return this.subCourses; } for Subcourse it generates @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "course_id", nullable = false) public Course getCourse() { return this.course; } Now the problem is that cascading does not work as expected. I want to

问题 In Oracle, to drop the constraint PK_SAI I use the syntax: ALTER TABLE "SAISIE" DROP CONSTRAINT "PK_SAI" CASCADE; What is the equivalent of this in SQL Server? 回答1: You are thinking of the CASCADE feature on FOREIGN KEY constraints, in relation to actual DELETE statements. ALTER TABLE t2 add constraint FK_T2 foreign key(t_id) references t(id) ON DELETE CASCADE; Dropping a constraint with CASCADE does not delete any rows. DELETE deletes rows, if you have enabled ON DELETE CASCADE. Dropping the

问题 Since 2h I'm trying to come up with the solution for the following problem, and I just can't find a proper way to do it: I have three tables in MySQL db: Role [role_id] [role_name] Permission [permission_id] [permission_name] PermissionToRole [permission_id] [role_id] I have the Role class as the owner of the relationship: @ManyToMany(cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH}) @JoinTable(name="permissiontorole", joinColumns={@JoinColumn(name="role_id")},

问题 I am writing an ASP.NET MVC4 / Razor / C# based application that needs to render a grid of records. Each row has several columns, and there may be 100 or so rows. Each row has a checkbox field, text field and then three cascading dropdown lists. The first dropdown is prepopulated on page load. The second needs to be populated using Ajax on change of the first dropdown list. The third from a change on the second. Each row is separate and does not influence each other. What is the recommended

问题 I'm confident that this is possible but for the life of me I can't figure it out. What I have created is a user history MSSQL table to hold the changes made to a user and by whom. This table contains two foreign keys which reference my other table (User) - one fkey for the affected user and the other fkey for the user making the changes. What I need is for any changes to the (User) table to cascade and update the corresponding entries in this new table. The fields in the new table (User

问题 I am trying to figure out how cascade delete works. I know the general concept but not the specifics of it. I have 3 tables (a)||---|<(B)>o---||(C) Table A: Aid Tag Table B: Aid (f) Cid (F) Table C: Cid Other A row in table A must have at least one reference to table c or else it should be deleted. A row in table A is made only when Table C tries creating a tag that does not exist. If table C removes that tag and no other rows from table C reference that tag then the tag should be removed. If

问题 I am trying to save an entity that has a many-to-many association to another entity and cascade the persistence to the associated entity and create the association using spring data jpa repository. I can insert the parent entity_a which contains a set of entity_b using entityARepository.save(entityA) . Spring jpa is taking care of all the inserts needed in the transaction. All the entity_b's get inserted, entity_a's get inserted and the join table in the middle has the association inserted as

问题 I have an Application object and some Form objects. Each time a Form is saved, I would like to update Application.lastUpdated. Application has an EntityListener which I want to use to set Application.lastUpdated for me. When I save Application, the EntityListener is called and it works. However when I save Form the EntityListener is not called. I can see this via debugging and via the fact that the lastUpdated field does not change. The Form has a one-way OneToOne relationship with the

问题 i am using Entity Framework with code first approach. In my onModelCreating I am creating my tables with keys and relationships (I am using Fluent API approach, not data annotations). But when I try to generate my model using Update-Database command I receive following error Introducing FOREIGN KEY constraint 'FK_customers.invoices_customers.billingCenters_billingCenterId' on table 'invoices' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or