unique « Key « JPA Q&A

1. Making foreign keys unique in JPA    stackoverflow.com

Is it possible to make a foreign key unique within a table? Suppose I have entities A and B. A:

class A extends Serializable {
private long id;

private B b;
class B extends Serializable {
private long ...

2. one-to-one with just unique keys    forum.hibernate.org

property-ref: The name of a property of the associated class that is joined to the primary key of this class. I'm not sure how that helps, since it still involves a primary key. I can see how to do this if I get rid of the synthetic key, USER_ID, and simply use the ORACLE_ID field as the PK. But then I'm ...

3. how to use unique-key    forum.hibernate.org

hi i am trying group columns together in a table so they have unique value Mysql ddl looks like this CREATE TABLE table1( id bigint(20) NOT NULL auto_increment, col1 bigint(20) NOT NULL, col2 bigint(20) NOT NULL, col3 bigint(20) NOT NULL, col4 bigint(20) NOT NULL, UNIQUE KEY (col2,col3,col4), PRIMARY KEY(id) ) TYPE=MyISAM; these r the ways i found in the HBRD 1) ...

4. non-unique "key" in legacy table    forum.hibernate.org

Author Message suffolksoft Post subject: non-unique "key" in legacy table Posted: Fri Apr 15, 2005 10:55 am Newbie Joined: Tue Jan 04, 2005 11:06 am Posts: 15 I will risk the wrath of the Etiquette Police by re-posting this question with a slightly different twist. The original post was buried as a response to a related topic and perhaps ...

5. secondary unique key and reordered operations    forum.hibernate.org

Hibernate version: 3.0.5 I run into the problem where a database table (legacy system) defines a secondary unique key on a table which hibernate do not take into account during "reordering" of its database operations. Mainly I delete all records and reimport new records out of a csv file. Maybe there are the same records in this file maybe not. Using ...

6. Many-To-Many via two columned Unique-Key    forum.hibernate.org

Hibernate version: 3.1.3 Anything else: Inside the text Hello, I have a problem that I just cannot cope. It is about the in the forum already discussed topic of an many-to-many relationship with extra attributes in the association table. The table structure is unchangeable and is as follows: Code: CREATE TABLE `message` ( `id` int(11) NOT NULL, ...

7. unique key as foreign key    forum.hibernate.org

Newbie Joined: Mon Sep 25, 2006 12:35 am Posts: 1 Quote: when i use the primary key of one table as a foreign key for another i have no problems but when i use a unique key i get an error... is it possible for me to use unique key as my foreign key in another table the following code is ...

8. many-to-one and unique for 1:1 with foreign key    forum.hibernate.org

Hello, I am new to hibernate and having problems to get a 1:1 (i.e. person-address) foreign key relationship (many-to-one with unique=true) to work (see doc page 61). Question: Could someone please send me an example (with coding) or a reference to an 1:1 foreign key realtionship example that works and solves this problem? Thank you! All the best Michael

9. unique-key help needed    forum.hibernate.org

Beginner Joined: Fri Apr 15, 2005 3:30 pm Posts: 46 Location: Fortaleza, Brazil Need help with Hibernate? Read this first: Hibernate version: 3.2 Mapping documents: Code:

10. Unique foreign key    forum.hibernate.org

Hi, I have a table with three fields - a primary key, a unique foreign key and another varchar field. I want to use saveOrUpdate() in the corresponding hibernate code. I want to modify the varchar field if the foreign key value already exists. But it is throwing unique constraint violation (org.hibernate.exception.ConstraintViolationException). Can I use saveOrUpdate in such a situation? Otherwise ...

11. mulitple unique-key groups    forum.hibernate.org

12. unique-key    forum.hibernate.org

Hi I am trying to generate a unique-key for a table. I have read the docs and tried what it said but still am unable to achieve desired results Eg But I am still able to insert the same data more than once. ...