toplink

问题 I found some hint in Toplink Query query = em.createQuery("SELECT e FROM Employee e ORDER BY e.lastName ASC, e.firstName ASC"); query.setHint("eclipselink.cursor.scrollable", true); ScrollableCursor scrollableCursor = (ScrollableCursor)query.getSingleResult(); List<Employee> emps = scrollableCursor.next(10); is there are jpa/hibernate alternative? 回答1: To my knowledge, there is nothing standard in JPA for that. With Hibernate, the closest alternative I'm aware of would be the Query /

问题 As far as I know, JPA itself offers all the shiny features like ORM, JPQL, entity relations mapping and so on. But I don't really understand, why do people use Hibernate or Toplink on top of JPA. What does Hibernate offer that JPA itself doesn't have? 回答1: JPA is just a specification. Hibernate and TopLink are implementations of that specification. Also, the JPA spec is a bit weak, it provides only a subset of the functions that the likes of Hibernate and TopLink provide. Sometimes it is

问题 I am using EclipseLink libraries in eclipse (at dev time) and deploy on TopLink, I need to show the generated sql statement. I am using the following persistence.xml: <?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"> <persistence-unit name="myPUnit"

问题 Is there any way if executing batch updates (EntityManager persist() or merge()) using JPA Toplink? 回答1: If you want to do a batch update, you can create a Query (either JPQL or Native SQL) that performs the update using the EntityManager, and then call executeUpdate on that query. 来源： https://stackoverflow.com/questions/7365325/batch-updates-in-jpa-toplink

问题 Is it possible to do a nested select in JPA QL? How would I write the following SQL statement in JPA QL? select * from preferences p left outer join (select * from preferencesdisplay where user_id='XXXX') display on ap.pref_id=display.pref_id; The JPA entity PREFERENCES has a OneToMany relationship to PREFERENCESDISPLAY . I want to get all the PREFERENCES whether or not there is a PREFERENCESDISPLAY reference. 回答1: In hibernate you can use "with": select ... from Preferences p left join p

问题 How can i display below toplinks in footer, i used below code in Footer.phtml file, <?php echo $this->getChildHtml('topLinks'); ?> but the links are not displayed?. How can i do this? Thanks in advance footer.phtml <div class="footer-container"> <div class="footer"> <?php echo $this->getChildHtml() ?> <?php echo $this->getChildHtml('newsletter') ?> <?php //echo $this->getLayout()->createBlock('cms/block')->setBlockId('sample_links')->toHtml() ?> <?php echo $this->getChildHtml('samplelinks') ?

问题 I am currently working on a project that uses JPA (Toplink, currently) for its persistence. Currently, we are running a single application server, but, for redundancy, we would like to add a load balancer and another application sever (and possibly more as it grows). First, I'm running into the issue of JPA caching. Since two processes will be updating the same database, the JPA cache returns the cached value rather than going to the database. I see how to turn that off, and the database

问题 Hi I'm new to JPA and I'm having trouble understanding how it handles inheritance. I have a specific problem I need solved without changing the DB scheme, but if you can't find a solution I would appreciate solution suggestions with a different DB scheme (Hibernate/TopLink solutions welcome). If I was unclear or you need more information, please tell me so. Thanks in advance! I have this database: TABLE Fruit Id Varchar (10) Primary Key size Varchar (10) fruit_type Varchar(10) TABLE Apple Id

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 6 years ago . I have made use of the following JPA implementations: Hibernate, Toplink, OpenJPA Each of them has their own strengths and weaknesses.

问题 I have an existing database of a film rental system. Each film has a has a rating attribute. In SQL they used a constraint to limit the allowed values of this attribute. CONSTRAINT film_rating_check CHECK ((((((((rating)::text = ''::text) OR ((rating)::text = 'G'::text)) OR ((rating)::text = 'PG'::text)) OR ((rating)::text = 'PG-13'::text)) OR ((rating)::text = 'R'::text)) OR ((rating)::text = 'NC-17'::text))) I think it would be nice to use a Java enum to map the constraint into the object