ObjectDB ObjectDB

Internal Website Search

81-90 of 200 resultsRefresh

ORDER BY clause (JPQL / Criteria API)

clause produces objects for examination and the WHERE clause selects which objects to collect as results ... . The following query returns Country objects ordered by currency as the primary sort key and by name as ... above: SELECT c.currency AS currency, c.name AS name FROM Country c ORDER BY currency, name

Date and Time in JPQL and Criteria Queries

Date and time expressions may appear in JPQL queries: as date and time literals - e.g. {d '2011-12-31'}, {t '23:59:59'}. as parameters - when date and time values are assigned as arguments. as path expressions - in navigation to persistent date and time fields. as results of predefined JPQL current

Defining a JPA Entity Class

(annotated) as having the ability to represent objects in the database. Conceptually this is similar to serializable classes, which are marked as having the ability to be serialized. The Point Entity Class The following Point class, which represents points in the plane, is marked as an entity class

Collections in JPQL and Criteria Queries

Collections may appear in JPQL queries: as parameters - when collections are assigned as arguments. as path expressions - in navigation to persistent collection fields. IS [NOT] EMPTY The IS [NOT ... , which should be used for checking other collections, such as a collection that is passed to the query

Database Schema Evolution

and either the same type or a convertible type, as explained below. A matching field ... int to Date) the fields are not considered as matching and the new field is initialized ... that are stored as numeric ordinal values (the default). From any type to Boolean or boolean (0, null

Index Definition

; } When indexed fields are specified explicitly in the members attribute, as shown ... , the @Uniques annotation can wrap multiple @Unique annotations. As shown above, the members attribute ... to values that are stored as part of the entity. Therefore, indexes on multi part paths

Logical Operators in JPQL and Criteria API

of logical operators, as shown in the following table: Set 1 - JPQL / SQL Set 2 - Java / JDO AND && OR ... /JDO && operator as a synonym of AND as part of its JDO support. Binary OR (||) Operator ... || operator as a synonym for OR as part of its JDO support. Unary NOT (!) Operator The following query

JPA Persistence Unit

to instantiate an EntityManagerFactory in JPA (as explained in the JPA Overview section) requires ... that is described in this manual can be replaced by equivalent XML in the mapping files (as ... , username and password, as demonstrated above. XML Mapping Metadata ObjectDB supports using XML metadata


. Building Queries with createQuery As with most other operations in JPA, using queries starts with an EntityManager (represented by em in the following code snippets), which serves as a factory ... and q2. When building a TypedQuery instance the expected result type has to be passed as an additional

Locking in JPA

that manage the same Employee database object, which is referenced as e1 by em1 and as e2 by em2 (notice ... is active, as so:   em.lock(employee, LockModeType.NONE); Other Explicit Lock Modes In addition ... defines additional lock modes that can also be specified as arguments for the lock method to obtain

Getting Started

ObjectDB is very easy to use. Follow the Getting Started Tutorial and the Quick Tour manual chapter and in minutes you may be able to write and run first Java programs against ObjectDB.

Prior knowledge or experience in database programming (SQL, JDBC, ORM, JPA, etc.) is not required, but some background in using the Java language is essential.

Need Help?

  1. Search ObjectDB website
  2. Read the FAQ
  3. Follow the Tutorials
  4. View or post in the forum
  5. Search or file an issue
  6. Contact support