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CRUD Database Operations with JPA

objects in the database by using a simple query: Query q1 = em.createQuery("SELECT COUNT(p) FROM ... COUNT(p) FROM Point p") instructs JPA to count all the Point objects in the database ... see another example of a query that returns a single result: Query q2 = em.createQuery("SELECT AVG(p.x) FROM

Index Definition

, long, float, double. Equivalent wrapper classes from package java.lang: Byte, Short, Character, Integer ... query execution. Indexes are especially efficient in lookup and range queries: SELECT p FROM Point p WHERE p.x = 100 SELECT p FROM Point p WHERE p.x BETWEEN 50 AND 80 SELECT p FROM Point p

JPA Query Structure (JPQL / Criteria)

rather than just field values from database tables, as with SQL. That makes JPQL more object oriented friendly ... of up to 6 clauses in the following format: SELECT ... FROM ... [WHERE ...] [GROUP BY ... [HAVING ...]] [ORDER BY ...] The first two clauses, SELECT and FROM are required in every retrieval query

ObjectDB Object Database Features

attributes, grouping queries and aggregate queries) which are usually missing from Object Oriented ... can manage databases of various sizes efficiently, ranging from kilobytes to terabytes. Platform ... from failure by using a recovery file and double writing. Additional recovery layer - supports

Strings in JPQL and Criteria Queries

(when present) specifies from which position to start the search. LOWER and UPPER - Changing String Case ... ] FROM] str) function returns a string after removing leading and/or trailing characters (usually space characters). For example: TRIM(' UK ') is evaluated to 'UK'. TRIM(LEADING FROM ' UK ') is evaluated

JPA Persistable Types

only once even if they are referenced multiple times. Referencing instances of other persistable types from multiple ... . In most cases ObjectDB can overcome a missing no-arg constructor. Aside from these constraints ... : boolean, byte, short, char, int, long, float and double. Equivalent wrapper classes from package

Privacy Policy

to data collected automatically, either generated by the use of the Service or from the Service ... refers to ObjectDB Website, accessible from https://www.objectdb.com You means the individual ... or other governmental jurisdiction where the data protection laws may differ than those from

[ODB1] Chapter 7 - JDOQL Queries

There are various ways to retrieve objects from an ObjectDB database, as shown in section 6.3 ... for RDBMS. It provides object retrieval from the database according to a specified selectioPlan ... is a subset of objects from the candidate collection that contains only the instances of the candidate class

[ODB1] Chapter 5 - JDO Connections

PersistenceManager instances. From the developer's point of view, connection pool management ... () method is the same for both new database connections and database connections obtained from a pool ... for all the transactions of PersistenceManager instances obtained from that factory. Setting these flags


) Delete the persistent instance from the data store. Delete the persistent instance from the data ... of the instance is not deleted from the data store. This method has no effect if the instance ... void deletePersistentAll(Object... pcs) Delete an array of instances from the data store. Delete

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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