Visit the new documentation for updated content. DB4O. Table of contents. 1 Info; 2 The Basic Principle of db4o; 3 Downloads; 4 Current Status. This tutorial was written to get you started with db4o as quickly as possible. Before you The API documentation for db4o is supplied as a compiled Help file . db4o provides sources of documentation: tutorial, reference documentation, API documenation, online paircasts and.
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Native Queries also provide type safetyas well as remove the need to sanitize against code injection see SQL Injection. Walks you through db4o’s basic operations, its various query types, and techniques for optimal data access performance.
When searching for Brian in the database, you therefore need only look documentatioon those attributes on the Person instances. Setting the ActivationDepth to 0 will cause nothing to be activated. NET version includes the corresponding Compact Framework release. Depending on the features your application requires, reference and distribute these assemblies when you distribute your application:. From Wikipedia, the free encyclopedia.
Calling Store with 2 User objects both with an ID of “jack” will result in 2 separate instances. And for those documentatino where db4o’s native query facility fails to meet the need, the SODA API which originally appeared as a standalone query system for any object system, and still lives on SourceForge allows you to tune the query down to its tiniest detail, at the expense of simplicity.
While a db4o database file is open, it is locked and cannot be accessed by another application at the same time. The busy Java developer’s guide to db4o Stay tuned for additional content dn4o this series.
This series is a working introduction to db4o, an open source database that leverages today’s dochmentation languages, systems, and mindset. So you could Descend into an object, and then Execute at a deeper level to return only the matching child objects, like in this example:. If the database is not closed cleanly, or if the application crashes at any time and uncommitted or incomplete transactions are discarded. LINQ support is fully integrated in db4o for.
Object data is activated as the users accesses each object in the result set. Once that’s all done, I call get on the documwntation database and check to see if the ObjectSet returned contains any objects. Because QBE uses a prototype object as its template to search for data, documentatino are a few simple rules regarding its usage. Setting the UpdateDepth to 0 will prevent any changes documetation being saved to the database. Refcard Getting Started With db4o.
About this series Information storage and retrieval has been nearly synonymous with RDBMS for about a decade now, but recently that has begun to change. SODA query expressions are a standard that was present in all but the documentatoin versions of db4o. For all but the simplest db4o use cases, you’ll probably want to specify one or more configuration settings when opening your db4o database:.
Special cases can be handled through writing custom type handlers.
You can then call the Activate object, depth method to manually activate the object as described above. For string values, behaves as Like. Accordingly, when you call setdb4o knows to update dofumentation existing object rather than insert a new one.
Db4o – Wikipedia
In OctoberActian declined to continue to actively pursue and promote the commercial db4o product offering for new customers. Notice how each of the calls to Constrain will return an IConstraint?
Getting Started With db4o
Please help improve it or discuss these issues on the doocumentation page. However, if you retrieve the user, and modify the first instance, then store it again, you will have only 1 updated instance in the database.
When dealing with objects that may have relations to other objects quite deep think of documentatikn path of data from Customer to Order to OrderItem to Documentatioon with relations to Address objects for billing and shipping and then PO and payment transactions it would be quite expensive to have to pull all of that data into memory from the DB if all you wanted was the Customer object.
This article contains content that is written like an advertisement. For strings, matching documentxtion will contain the supplied value anywhere within the match. One of its main goals is to provide an easy and native interface to persistence for object oriented programming languages. It can also be used as an abstraction layer, allowing to easily switch the underlying database technology.
What you need is a utility method to simplify identity-based searches. The ODB is primarily used as an application specific database in either extreme scale systems or embedded systems where typical DBA activities are automated. A full description of LINQ syntax docuentation not fit in this document. Developers using relational databases can view db40 as a complementary tool. QBE lets you pass db4o an example object. Properties of the 5th descendant object will have their values left as default or null.
Microsoft Visual Studio Express editions are available for free download from Microsoft. Over a million developers have joined DZone. All of an object’s properties and child objects will be stored.