About empty

forum_thread

Some details about db behavior

Suppose I have two entities... A B -> A B has a ManyToOne relationship with A. When my database is empty and I persist a valid B entity (that contains actual A reference) I observe some behaviour that I'm not sure I understand. ... ManyToOne relationship with A. When my database is empty and I persist a valid B entity (that contains actual A reference) I ...

 
api-jpa

getOrderList()

Return the ordering expressions in order of precedence.(Method of javax.persistence.criteria.CriteriaQuery)

 
forum_thread

the tutorial netbeans and javaee6 dont work,

hi . i am Mauro . i have tried the tutorial for the objectDB and netbeans and JAvaee6 I have insert the persistencex.ml like tutorial (for the embedded mode) . but when i have insert the name into form for to save the new guest into db , i get the following message from glassfsih:   HTTP Status 404 - -------------------------------------------------------------------------------- type Status report message ... Your project has 2 problems: The servlet is empty - it seems that you missed step 4 . There is an ...

 
forum_thread

How to avoid NULL values on Embedded entities

Hi there. I'm new on this. trying to learn. I'm trying to make a value non nulleable. So, when I try to upload to the DB this field as null, it give me an error. I tried this, but it didn't work: ... code was working, the problem was that i'm savin an empty string "" (not null) edit ...

 
forum_thread

Bidirectional OneToMany is slow on updated items

Hello, I have a problem with the following situation. I insert persons with addresses. In the first run, they are all new with a new address. It runs fast. In the second run, the persons are all loaded and got a second address. This seams to be much slower. The Entities are all enhanced by the javaagent (which you can see in the contained eclipse launch configuration) Is there any way to speed it up?       ... the addressSet retrieval when the database is not empty. A simple action that can improve performance dramatically, is to ...

 
api-jpa

javax.persistence.criteria.Fetch

Represents a join-fetched association or attribute.(Interface of JPA)

 
api-jpa

getSingularAttributes()

Return the single-valued attributes of the managed type.(Method of javax.persistence.metamodel.ManagedType)

 
forum_thread

LEFT (OUTER) JOIN problem when mappedBy is defined

Hi all, I want to get objects with their lists, even when the lists are empty. So I've witten this query: "SELECT i FROM Invoice i LEFT OUTER JOIN i.itemList items" But this query never returns invoices without items! Only invoices with items. When I remove mappedBy from @OneToMany annotation, LEFT JOIN works correctly. Is this normal behaviour? Thank you Michael   Sample application ... to get objects with their lists, even when the lists are empty. So I've witten this query: "SELECT i FROM Invoice i LEFT ...

 
api-jpa

javax.persistence.criteria.CriteriaBuilder.In

Interface used to build in predicates.(Interface of JPA)

 
api-jdo

Constants.ANONYMOUS_PERSISTENCE_MANAGER_FACTORY_NAME

The name of the anonymous PersistenceManagerFactory, which is the empty string.(Static Field of javax.jdo.Constants)