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Paths and Types in JPQL and Criteria API

subinterfaces of From (Root, Join) - The creation of a FROM expression automatically modifies

ObjectDB Website - Terms and Conditions of Use

, and under this license you may not: modify or copy the materials; use the materials for any commercial purpose

JPA Primary Key

Every entity object that is stored in the database has a primary key. Once assigned, the primary key cannot be modified. It represents the entity object as long as it exists in the database. As an object database, ObjectDB supports implicit object IDs, so an explicitly defined primary key is not


Returns: the modified query Since: JPA 2.0 Root<X> from(Class<X> entityClass) Create and add a query ... expressions Returns: the modified query Since: JPA 2.0 AbstractQuery<T> groupBy( Expression... grouping ... are simply removed. Parameters: grouping - zero or more grouping expressions Returns: the modified


phenomena can occur: P1 (Dirty read): Transaction T1 modifies a row. Another transaction T2 then reads that row and obtains the modified value, before T1 has committed or rolled back. Transaction T2 ... . Another transaction T2 then modifies or deletes that row, before T1 has committed. Both transactions eventually

Step 3: Define an EJB Session Bean

using JTA - no need to wrap every operation that modifies the database (such as persist) by

[ODB1] Chapter 7 - JDOQL Queries

using any method that does not modify persistent objects, including instance methods and static

[ODB1] Chapter 1 - About ObjectDB

(for example, as a result of special customer needs or requests) can be done without modifying code. The JDO


modifies the class to implement PersistenceCapable prior to loading the class into the runtime ... returns the current object id as modified in the current transaction. Returns: a copy of the ObjectId of this instance as modified in the transaction. Since: JDO 1.0 See Also: jdoGetObjectId


. Returns: a copy of the ObjectId of the parameter instance as modified in this transaction ... modified in this transaction. Since: JDO 2.0 See Also: PersistenceCapable.jdoGetVersion() Boolean ... . Instances that have been modified, deleted, newly made persistent in the current transaction, or

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.

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