ObjectDB ObjectDB

Internal Website Search

101-110 of 200 resultsRefresh
12

Paths and Types in JPQL and Criteria API

classes) are represented in JPQL by the following types of expressions: Variables - FROM ... as arguments. Path expressions that navigate from one object to another. Instances of user defined ... .capital.name is a nested path expression that continues from the Capital entity object to its name
11

ORDER BY clause (JPQL / Criteria API)

is at least one million people, ordered by the country name: SELECT c.name FROM Country c WHERE c.population > 1000000 ORDER BY c.name When an ORDER BY clause exists it is the last to be executed. First the FROM ... from expressions in the SELECT clause are allowed in the ORDER BY clause. The following query
10

WHERE clause (JPQL / Criteria API)

The WHERE clause adds filtering capabilities to the FROM-SELECT structure. It is essential in any JPQL query that retrieves selective objects from the database. Out of the four optional clauses ... FROM Country c WHERE c.population > :p The FROM clause of this query defines an iteration
10

DELETE Queries in JPA/JPQL

As explained in chapter 2, entity objects can be deleted from the database by: Retrieving the entity objects into an EntityManager. Removing these objects from the EntityManager within an active ... an alternative way for deleting entity objects. Unlike SELECT queries, which are used to retrieve data from
10

GROUP BY and HAVING clauses

clause in the query execution order is after the FROM and WHERE clauses, but before the SELECT ... ) that are generated by the FROM clause iteration and pass the WHERE clause filtering (if any) are sent ... .name, 1, 1) FROM Country c GROUP BY SUBSTRING(c.name, 1, 1); The FROM clause defines iteration
9

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
9

Database Schema Evolution

), a conversion is required. If the old type is inconvertible to the new type (for instance a change from ... with a default value (0, false or null). The following type conversions are supported: From any numeric type ... that are stored as numeric ordinal values (the default). From any type to Boolean or boolean (0, null
1

[ODB1] Chapter 9 - ObjectDB Explorer

the Explorer. You can also start the Explorer from the command line. For instance, if the installation ... is open. The "Class" window shows all the persistent classes in the database. You can select a class from ... from the auto completion list when you write the query filter and also when you fill the ordering field
0

[ODB1] Chapter 8 - ObjectDB Server

these databases from remote machines by TCP/IP. More details about client server mode vs. embedded database ... program You can run the server as a Java program from the command line, as so: > java -cp <OBJECTDB ... is restricted to connect to the server only from the specified IP address. For instance, the "127.0.0.1
0

[ODB1] Chapter 3 - Persistent Classes

metadata declaration. Chapter 4 explains how to write the JDO metadata declaration. Aside from ... constructors, methods, fields, attributes (final, abstract, public), inheritance (even from a non persistent ... can never be persistent. The transient modifier can be used to exclude other fields from being stored in

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