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.
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Every entity object that is stored in the database has a primary key. Once assigned, the primary ... an object database, ObjectDB supports implicit object IDs, so an explicitly defined primary key is not required. But ObjectDB also supports explicit standard JPA primary keys, including composite primary
Explains how to define and use JPA entity classes and other JPA persistable types.
support of the JPA and JDO APIs. Fundamental features of relational databases (e.g. primary keys, derived ... classes. Primary Keys Support of primary keys in ObjectDB is unique compared to other Objec-Oriented Databases. Primary Key Modes Hidden - primary key is automatically managed by ObjectDB with no @Id field
key of a managed object", but my application is not trying to change the primary key. (ObjectDB log ... is StringIdentity. Note that StringIdentity is defined in JDO to represent a combination of class + primary key ... + primary key is needed. This may solve the exception. Anyway, StringIdentity as a primary key field type
and recommendations, in particular there are some primary keys with value == 0. These cause problems for objectDB, typically "JPA Unexpected argument as primary key". When using eclipselink, there is a workaround ... have a zero value in primary key column -->
@OneToOne association that has a shared primary key, example: http://fruzenshtein.com/bidirectional-one-to-one-primary-key-association/ Can ObjectDB support this same specific relationship ... . You can have a bidirectional one to one association, but it cannot be based on identical primary keys, i.e
Primary Key with two Longs b) Embedded Primary Key with two Longs c) Furthermore, as String ... engine. In both cases it is a composite primary key with the same size and structure. (b) requires ... Can you give us a recommendation as we can represent the Key (UUID) most efficient? Both in terms
keep getting errors : Attempt to reuse an existing primary key value... My primary keys are annotated
should fix it. The composite primary key issue is unclear, since switching to a single primary key
that, and query the table all the PK fields are null or 0. What can I do to modify primary keys? Trianglehead Json Error ObjectDB doesn't support changing primary keys, as it may break references to objects