qr barcode generator vb.net SELECT UPDATE DELETE in Software

Making Denso QR Bar Code in Software SELECT UPDATE DELETE

SELECT UPDATE DELETE
Scan QR Code In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Draw Quick Response Code In None
Using Barcode creation for Software Control to generate, create QR Code ISO/IEC18004 image in Software applications.
ejbLoad() ejbStore() ejbRemove()
QR-Code Decoder In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
QR-Code Generation In Visual C#
Using Barcode drawer for VS .NET Control to generate, create Quick Response Code image in Visual Studio .NET applications.
TABLE 22-1
Paint QR In Visual Studio .NET
Using Barcode creation for ASP.NET Control to generate, create QR-Code image in ASP.NET applications.
QR Code Generator In Visual Studio .NET
Using Barcode generation for .NET framework Control to generate, create QR-Code image in .NET applications.
Corresponding Database and EJB Activities
Drawing Quick Response Code In VB.NET
Using Barcode creation for VS .NET Control to generate, create QR Code JIS X 0510 image in .NET applications.
Creating Code 128C In None
Using Barcode maker for Software Control to generate, create Code-128 image in Software applications.
22:
Barcode Creator In None
Using Barcode generation for Software Control to generate, create bar code image in Software applications.
Bar Code Creator In None
Using Barcode drawer for Software Control to generate, create barcode image in Software applications.
SQL and Application Servers
UPC Code Printer In None
Using Barcode drawer for Software Control to generate, create UPC-A image in Software applications.
Print EAN 13 In None
Using Barcode creator for Software Control to generate, create UPC - 13 image in Software applications.
Note that entity beans are always stateful the distinction between these two bean types is not the difference between stateless and stateful beans, but rather, the difference between who is responsible for maintaining proper state. The next two sections discuss the practical issues associated with each type of entity bean, and the trade-offs between them.
Print ITF In None
Using Barcode creator for Software Control to generate, create 2/5 Interleaved image in Software applications.
Data Matrix 2d Barcode Drawer In Visual Studio .NET
Using Barcode generation for Reporting Service Control to generate, create Data Matrix image in Reporting Service applications.
Using Container-Managed Persistence
Code128 Generation In Visual C#
Using Barcode maker for .NET framework Control to generate, create USS Code 128 image in Visual Studio .NET applications.
UCC.EAN - 128 Generator In None
Using Barcode generator for Microsoft Excel Control to generate, create USS-128 image in Excel applications.
An entity bean s deployment descriptor specifies that an entity bean requires containermanaged persistence. The deployment descriptor also specifies the mapping between instance variables of the bean and columns in the underlying database. The deployment descriptor also identifies the primary key that uniquely identifies the bean and the corresponding database row. The primary key value is used in the database operations that store and retrieve variable values from the database. With container-managed persistence, the EJB container is responsible for maintaining synchronization between the entity bean and the database row. The container calls JDBC to store instance variable values into the database, to restore those values, to insert a new row into the database, and to delete a row all as required by actions on the bean. The container will call the bean s ejbStore() callback method before it stores values in the database, to notify the bean that it must get its variable values into a consistent state. Similarly, the container will call the bean s ejbLoad() callback method after loading values from the database, to allow the bean to do appropriate postprocessing (for example, calculating a value that was not itself persisted, based on values that were). In the same way, the bean s ejbRemove() method will be called before the container deletes the row from the database, and ejbCreate() and ejbPostCreate() are called in conjunction with inserting a new row. For many entity beans, these callback methods will be empty, since the container handles the actual database operations.
Data Matrix 2d Barcode Decoder In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
Drawing EAN 13 In Java
Using Barcode creation for Android Control to generate, create UPC - 13 image in Android applications.
Using Bean-Managed Persistence
Bar Code Generator In Objective-C
Using Barcode printer for iPad Control to generate, create barcode image in iPad applications.
EAN-13 Maker In None
Using Barcode creation for Word Control to generate, create EAN13 image in Office Word applications.
If an entity bean s deployment descriptor specifies bean-managed persistence, the container assumes that the entity bean will handle its own database interaction. When a new entity bean is first created, the container calls the bean s ejbCreate() and ejbPostCreate() methods. The bean is responsible for processing the corresponding INSERT statement for the database. Similarly, when an entity bean is to be removed, the container calls the bean s ejbRemove() method. The bean is responsible for processing the corresponding DELETE statement for the database, and when the bean returns from the ejbRemove() method, the container is free to actually remove the bean itself and reuse its storage. Bean loading is similarly handled by a container call to ejbLoad(), and storing by a call by the container to ejbStore(). The bean is similarly notified of passivation and activation by callbacks from the container. Of course, nothing limits the entity bean s database interaction to these callback methods. If the bean needs to access the database during the execution of one of its methods, the bean can make whatever JDBC calls it needs. The JDBC calls within the callback methods are strictly focused on managing bean persistence.
PART VI
Part VI:
SQL Today and Tomorrow
Container-Managed and Bean-Managed Trade-Offs
You might naturally ask why you would ever want to use bean-managed persistence when container-managed persistence eliminates the need to worry about synchronizing with the database. The answer is that container-managed persistence has some limitations: Multiple databases For most application servers, entity beans must be mapped into a single database server. If entity bean data comes from multiple databases, then bean-managed persistence may be the only way to handle database synchronization. Multiple tables per bean Container-managed persistence works well when all of the instance variables for an entity bean come from a single row of a single table that is, when there is a one-to-one correspondence between bean instances and table rows. If an entity bean needs to model a more complex object, such as an order header and individual line items of an order, which come from two different, related tables, bean-managed persistence is usually required, because the bean s own code must provide the intelligence to map to and from the database. Performance optimizations With container-managed persistence, a container must make an all-or-nothing assumption about persisting instance variables. Every time the variables must be stored or loaded, all of the variables must be handled. In many applications, the entity bean may be able to determine that depending on its particular state, only a few of the variables need to be processed. If the entity bean holds a lot of data, the performance difference can be significant. Database optimizations If the methods of an entity bean that implement its business logic involve heavy database access (queries and updates), then some of the database operations that the container will carry out in a container-managed persistence scheme may be redundant. If bean-managed persistence is used instead, the bean may be able to determine exactly when database operations are required for synchronization and when the database is already up to date. In practice, these limitations often prevent the use of container-managed persistence in today s deployments. Enhancements in newer versions of the EJB specification are designed to address many of these shortcomings. However, bean-managed persistence remains a very important technique with the currently available application servers.
Copyright © OnBarcode.com . All rights reserved.