Solution Guide for Migrating Oracle on UNIX to SQL Server - Willy .Net

<strong>Solution</strong> <strong>Guide</strong> <strong>for</strong> <strong>Migrating</strong> <strong>Oracle</strong> on UNIX to SQL Server on Windows 271●Data providerDataSetThe DataSet is a copy of the data retrieved from the database cached in memory. Datacan be loaded into a DataSet from any valid data source, such as a SQL Serverdatabase, or an XML file. The DataSet persists in memory, and the data therein can bemanipulated and updated independent of the database. When appropriate, the DataSetcan then be used <strong>for</strong> updating the database.Data ProviderA data provider <strong>for</strong>ms the link between the Visual Basic .NET program and the database.A data provider is not a single component; rather it is a set of related components thatwork together to provide data in an efficient, per<strong>for</strong>mance-driven manner.Two data providers are available <strong>for</strong> Visual Basic .NET. The SQL Server Data Provider isdesigned specifically to work with SQL Server 7 or later, and the OLE DB Data Provider,which can also connect to other types of databases. Each data provider consists ofversions of the following generic component classes:● The Connection object provides the connection to the database.● The Command object executes a command against a data source. It can executenon-query commands, such as INSERT, UPDATE, or DELETE, or return aDataReader with the results of a SELECT command.● The DataReader object provides a <strong>for</strong>ward-only, read-only, connected recordset.● The DataAdapter object populates a disconnected DataSet or DataTable with dataand per<strong>for</strong>ms updates.The following classes are also offered: Transaction, CommandBuilder, Parameter,Exception, Error, and ClientPermission.For more in<strong>for</strong>mation on data provider components, refer tohttp://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconusingadonetproviderstoa ccessdata.asp.Even though the syntax and use of the functions differ, ADO.NET provides equivalentdatabase functions <strong>for</strong> SQL Server. It is important to ensure that these functions aretranslated to the new environment during the rewriting process.Scenario 1: Rewriting Pro*C to the .NET Plat<strong>for</strong>mRewriting the application <strong>for</strong> Windows makes use of native SQL Server APIs, ADO.NET,Microsoft ActiveX Data Objects (ADO), or Open Database Connectivity (ODBC) runningnatively in the Windows subsystem. Rewriting the application can result in a more stableand integrated configuration after the project is complete.Case 1: Rewrite the Application using Visual Basic.NETVisual Basic.NET provides all the functionality of the C programming language as well asseveral interfaces to SQL Server databases to execute SQL statements. This scenariodescribes how to rewrite a Pro*C application with Visual Basic .NET.The figure that follows shows a graphical representation of howthe Pro*C code willmigrate over to Visual Basic .NET during the rewrite.