Manipulate Advertisements Sample - DML Operations for LOB Columns Through ODP.NET Using C#

Table of Contents

• Objective of the Sample Application
• Overview of the Sample Application
• User Notes with Screen Shots
• Required Software
• Extracting the Sample
• Database Setup
• Preparing and Running the sample
• Description of Sample Files

The purpose of this sample application is to demonstrate:

1. How to perform DML operations on DataSet for LOB (Large Objects) columns like images, sound files etc.through ODP.NET using C#?

2. How to fetch BLOB data using OracleBLOB (ODP.NET type) and OracleDataReader through ODP.NET using C# ?

ODP.NET offers faster and reliable access to Oracle Database by using Oracle Native APIs. ODP.NET provides features to access any .NET application. The data access through ODP.NET can be done using a collection of classes contained in Oracle.DataAccess assembly. Figure 1.1 describes how data is accessed using ODP.NET. 

Figure 1.1: Accessing Data Using ODP.NET

DataSet is a major component of ADO.NET. It is an in-memory cache of the data retrieved from the database. OracleDataAdapter  represents a set of data commands and a database connection that is used to fill the DataSet based on the query given.  OracleCommand represents SQL statements to execute against datasource. OracleConnection is used to build the database connection. 

OracleDataReader is a read-only,  forward-only recordset. ExecuteReader method of  OracleCommand is used to create OracleDataReader. OracleBLOB is an OracleType specific to ODP.NET for accessing BLOB data from Oracle databases.

This sample is used to create/update/view advertisements for products. When this sample is run, a drop down list populated with products is displayed.The user can select a product from the list for which he/she wishes to create/update the advertisement.  The user can create a new advertisement or update an existing one by entering advertisement text in the text box and selecting image from the file-dialog, by clicking the 'Browse' button. 'Save' button can be clicked to commit changes and 'Close' button can be clicked to exit out of the application. Creating and updating advertisements demonstrates DML operations on DataSet for LOB data through Oracle Data Provider for .NET. Viewing advertisements demonstrates fetching  BLOB (LOB) data using OracleBLOB (ODP.NET type).

User Notes with Screen Shots

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When this sample application is run, a list of products populated from database is displayed. If the advertisement text and image already exists for the selected product then advertisement text and image is displayed as shown in figure 1.2 

Figure 1.2 Screen Shot for Manipulate Advertisement Sample Initial Screen

To insert/update an advertisement for a product selected from the list, the user can enter the value of Advertisement text.  To select an image for the advertisement, the user can click on 'Browse' button. A file dialog is displayed as shown in figure 1.3. 

Figure 1.3 Screen Shot displaying File Dialog Box For Image  

The selected image appears in the 'New Ad Image' picture box as shown in figure 1.4 . The user can commit the changes by clicking the 'Save' button.

Figure 1.4 Screen Shot After Selecting Image From File Dialog Box 

 The user can click on 'Close' button to exit from the application.

• Visual C# installed with MS Development Environment 7.0 version (MS Visual Studio .NET)  including MS .NET Framework 1.0 version  

• Oracle8i Database or later running SQL*Net TCP/IP listener (can be downloaded here )

• Oracle Data Provider for .NET (ODP.NET) (can be downloaded here )

Unzip DSDRwithLOB.zip using Winzip or command utility to your convenient directory referred to as <Extract_Dir>. Extraction of the zip file results in the creation of 'DSDRwithLOB' directory.  Refer Description of Sample Files section for more details.     

Connect to your database as any user and run the script <Extract_Dir>\DSDRwithLOB\Setup\DatabaseSetup.sql at the SQL prompt
SQL> @<Extract_Dir>\DSDRwithLOB\Setup\DatabaseSetup.sql

This script will prompt for the username, password and connectstring. You may choose any existing username. Following database objects will get created by running DatabaseSetup.sql file. 

Preparing and Running the Sample

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1. Ensure that the Database setup has been completed. 

2. Open DSDRwithLOB.sln using Visual Studio .NET from <Extract_Dir>\DSDRwithLOB folder. 

3. Edit ConnectionParams.cs file to change the database connection parameters i.e.Username, Password, TNSName for database .You need to input the same values of connection parameters as given while doing the Database Setup. Save this file.

4. Ensure that the following .NET Component References have been added to DSDRwithLOB project: 
          System, 
          System.Data, 
          System.Drawing, 
          System.Windows.Forms, 
          System.XML,
          Oracle.DataAccess. 

To add the above .NET Components 
a)Go to Menu ->View-> Solution Explorer. 
b)Right click on DSDRwithLOB project, choose 'Add Reference'. 
c)Choose the above .NET Components from the list displayed. 
d)Click 'Select', then OK. 
e) The chosen .NET component gets added to the project. 

5. Build and run the sample.

Following is the directory structure of the DSDRwithLOB.zip :

Please enter your comments about this sample in the OTN Sample Code Discussion Forum.