In this article, I'll explain the basic yet essential processes involved in building a .NET application that uses an Oracle database, including:

• How to add project references to support Oracle class libraries in your .NET project
• How to create Oracle Database connection strings
• How to work with Connection, Command, and DataReader objects

You will have the opportunity to apply what you have learned in three practice labs, ranging in difficulty from the relatively simple to the more complex. The article's screenshots are taken from Visual Studio 2008, but the experience is very similar in Visual Studio 2005.

For information and labs about how to secure your application, see my article "Securing a .NET Application on the Oracle Database". (Also, see the OTN .NET Developer Center for technical articles covering a range of Oracle.NET application lifecycle issues.)

Note that the free Oracle Developer Tools for Visual Studio, available for download from OTN, provides a Visual Studio add-in that makes the development of .NET apps on Oracle much easier and more intuitive. That subject is beyond our scope here, however.

.NET Data Provider

In addition to basic Oracle client connectivity software, .NET applications require the use of what is known as a managed data provider (where "managed" refers to code managed by the .NET framework). The data provider is the layer between the .NET application code and the Oracle client connectivity software. In almost every case, the best performance is achieved by using a provider optimized for a specific database platform instead of the generic .NET OLE DB data provider.

Oracle, Microsoft, and third-party vendors all offer .NET data providers optimized for Oracle. Oracle and Microsoft make their Oracle data providers available for free. (Microsoft's provider for the .NET Framework 2.0 is included in the framework, but it still requires Oracle client software installation.) In this article, we will use of the Oracle Data Provider for .NET (ODP.NET), which is included with the Oracle Database or as a separate download.

ODP.NET provides standard ADO.NET data access, while exposing Oracle database-specific features, such as XML DB, data access performance optimizations, and Real Application Clusters connection pooling.

When ODP.NET and Oracle client software are installed, application development using Visual Studio can begin. It's a good idea to confirm client connectivity before starting development. If you can connect to Oracle using Oracle client software such as SQL*Plus on the same machine as Visual Studio, then you know that your Oracle client-side software is properly installed and configured.

If you are new to Oracle, see the section "Installing .NET Products" in the Oracle Database 2 Day Developer's Guide for background information regarding installing and configuring ODP.NET specifically, or to the Oracle Database Documentation Library for general information about Oracle Database.

Creating a Project in Visual Studio 2005 or 2008

Let's create an ODP.NET application that retrieves data from an Oracle database. Later, we'll see how to perform error handling with ODP.NET and handle an additional data retrieval scenario.

After starting Visual Studio, the first task is to create a project. You can either select File | New | Project as shown below or click the New Project button located directly under File.

A New Project dialog box appears. On the left side of the dialog box under Project Types, select the programming language of your choice. In our example, "Visual Basic" was chosen. On the right side under Visual Studio installed templates, choose a project template. To keep things simple, a "Windows Forms Application" is selected.

You'll want to specify meaningful names for the project name (we used OraWinApp) and the solution name (we used OraWinApp). A solution contains one or more projects. When a solution contains only one project, many people use the same name for both.

Adding a Reference

Because our project must connect to an Oracle database, it is necessary to add a reference to the ODP.NET DLL containing the data provider of our choice. Within the Solution Explorer, select the project name, right click and select Add Reference. Alternatively, you can go to the menu bar and select Project and then select Add Reference.

The Add Reference dialog box appears.

ODP.NET is found under the Oracle.DataAccess component name. Select Oracle.DataAccess from the list, then click OK to make the ODP.NET data provider known to your project.

Visual Basic/C# Statements

After adding references, it is standard practice to add Visual Basic Imports statements or C# using statements. Technically, these statements are not required but they do allow you to refer to database objects without using lengthy, fully qualified names.

By convention, these statements appear at or near the top of a code file, before the namespace or class declaration.

Imports Oracle.DataAccess.Client ' Visual Basic ODP.NET Oracle managed provider

using Oracle.DataAccess.Client; // C# ODP.NET Oracle managed provider

If you added the reference, Intellisense will help you complete the addition of an Imports or using statement as shown in Figure 5.

Connection Strings and Objects

An Oracle connection string is inseparable from Oracle names resolution. Suppose you had a database alias of OraDb defined in a tnsnames.ora file as follows:

OraDb=
  (DESCRIPTION=
    (ADDRESS_LIST=
      (ADDRESS=(PROTOCOL=TCP)(HOST=ORASRVR)(PORT=1521))
    )
    (CONNECT_DATA=
      (SERVER=DEDICATED)
      (SERVICE_NAME=ORCL)
    )
  )

The OraDb alias defines the database address connection information for the client. To use the OraDb alias defined in the tnsnames.ora file shown above, you would use the following syntax:

Dim oradb As String = "Data Source=OraDb;User Id=scott;Password=tiger;" ' Visual Basic

string oradb = "Data Source=OraDb;User Id=scott;Password=tiger;"; // C#

You can modify the connection string to obviate the need for the tnsnames.ora file, however. Simply replace the name of the alias with how it would be defined in a tnsnames.ora file.

' Visual Basic
Dim oradb As String = "Data Source=(DESCRIPTION=" _
           + "(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=ORASRVR)(PORT=1521)))" _
           + "(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=ORCL)));" _
           + "User Id=scott;Password=tiger;"

// C#
string oradb = "Data Source=(DESCRIPTION="
             + "(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=ORASRVR)(PORT=1521)))"
             + "(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=ORCL)));"
             + "User Id=scott;Password=tiger;";

As you can see above, the username and password are embedded in the connection string in clear text. This is the simplest approach to creating a connection string. However, the clear text approach is undesirable from a security perspective. In particular, you must understand that compiled .NET application code is only marginally more secure than the clear text source code files. It is very easy to decompile .NET DLL and EXE files and view the original clear text contents. (Encryption is in fact the appropriate solution, but that subject would be a quite lengthy digression from our discussion here.)

Next, you must instantiate a connection object from the connection class. The connection string must be associated with the connection object.

Dim conn As New OracleConnection(oradb) ' Visual Basic

OracleConnection conn = new OracleConnection(oradb); // C#

Notice that the connection string is associated with the connection object by being passed through the object's constructor, which is overloaded. The constructor's other overload allows the following alternative syntax:

Dim conn As New OracleConnection() ' Visual Basic
conn.ConnectionString = oradb

OracleConnection conn = new OracleConnection(); // C#
conn.ConnectionString = oradb;

After associating a connection string with a connection object, use the Open method to make the actual connection.

conn.Open() ' Visual Basic

conn.Open(); // C#

We'll cover error handling later.

Command Object

The Command object is used to specify the SQL command text that is executed, either a SQL string or a stored procedure. Similar to the Connection object, it must be instantiated from its class and it has an overloaded constructor. In this sample, ODP.NET will perform a SQL query to return the department name (DNAME) from the departments table (DEPT) where the department number (DEPTNO) is 10.

Dim sql As String = "select dname from dept where deptno = 10" ' Visual Basic
Dim cmd As New OracleCommand(sql, conn)
cmd.CommandType = CommandType.Text

string sql = "select dname from dept where deptno = 10"; // C#
OracleCommand cmd = new OracleCommand(sql, conn);
cmd.CommandType = CommandType.Text;

Using different overloads, the syntax can be structured slightly differently. The Command object has methods for executing the command text, which will be seen in the next section. Different methods are appropriate for different types of SQL commands.

Retrieving a Scalar Value

Retrieving data from the database can be accomplished by instantiating an OracleDataReader object and using the ExecuteReader method, which returns an OracleDataReader object. Returned data is accessible by passing either the column name or zero-based column ordinal to the OracleDataReader.

Dim dr As OracleDataReader = cmd.ExecuteReader() ' Visual Basic
dr.Read()

Label1.Text = dr.Item("dname") ' retrieve by column name
Label1.Text = dr.Item(0) ' retrieve the first column in the select list
Label1.Text = dr.GetString(0) ' return a .NET data type
Label1.Text = dr.GetOracleString(0) ' return an Oracle data type

There are typed accessors for returning .NET native data types and others for returning native Oracle data types, all of which are available in C#, Visual Basic, or any other .NET language. Zero-based ordinals are passed to the accessors to specify which column to return.

OracleDataReader dr = cmd.ExecuteReader(); // C#
dr.Read();

label1.Text = dr["dname"].ToString(); // C# retrieve by column name
label1.Text = dr.GetString(0).ToString();  // return a .NET data type
label1.Text = dr.GetOracleString(0).ToString();  // return an Oracle data type

In this simplified example, the returned value of DNAME is a string and is used to set the value of the label control's text property, which is also a string. But if DEPTNO, which is not a string, had been retrieved instead, there would be a data type mismatch. The .NET runtime attempts to implicitly convert from one data type to another when the source and destination data types don't match. Sometimes the data types are incompatible and the implicit conversion fails, throwing an exception. But even when it works, it's still better to use explicit data type conversions instead of implicit data type conversion.

An explicit cast to integer is shown below:

Label1.Text = CStr(dr.Item("deptno")) ' Visual Basic integer to string cast

C# is not as forgiving as Visual Basic on implicit conversions. You'll find yourself doing explicit conversions: 

label1.Text = dr.GetInt16("deptno").ToString(); // C#

You can explicitly cast scalar values as well as arrays.

Close and Dispose

Either the connection object's Close or the Dispose method should be called to close the connection to the database. The Dispose method calls the Close method.

conn.Close()   ' Visual Basic
conn.Dispose() ' Visual Basic

conn.Close();   // C#
conn.Dispose(); // C#

You don't have to explicitly call Close or Dispose if you use VB's Using keyword or C#'s using keyword.

using (OracleConnection conn = new OracleConnection(oradb)) // C#
{
    conn.Open();

    OracleCommand cmd = new OracleCommand();
    cmd.Connection = conn;
    cmd.CommandText = "select dname from dept where deptno = 10";
    cmd.CommandType = CommandType.Text;

    OracleDataReader dr = cmd.ExecuteReader();
    dr.Read();

    label1.Text = dr.GetString(0);
}

In addition, OracleCommand includes a Dispose method; OracleDataReader includes a Close and Dispose method. Closing and disposing .NET objects free up system resources, ensuring more efficient application performance, which is especially important under high load conditions. You can experiment with some of the concepts we've learned here in Lab 1 (Retrieving Data from the Database) and Lab 2 (Adding Interactivity).

Error Handling

When an error occurs, .NET applications should gracefully handle the error and inform the user with a meaningful message. Try-Catch-Finally structured error handling is a part of .NET languages; here is a relatively minimalist example of using the Try-Catch-Finally syntax:

' Visual Basic
Try
    conn.Open()

    Dim cmd As New OracleCommand
    cmd.Connection = conn
    cmd.CommandText = "select dname from dept where deptno = " + TextBox1.Text
    cmd.CommandType = CommandType.Text

    If dr.Read() Then
        Label1.Text = dr.Item("dname") ' or use dr.Item(0)
    End If
Catch ex As Exception ' catches any error
    MessageBox.Show(ex.Message.ToString())
Finally
    ' In a real application, put cleanup code here.
End Try

// C#
try
{
    conn.Open();

    OracleCommand cmd = new OracleCommand();
    cmd.Connection = conn;
    cmd.CommandText = "select dname from dept where deptno = " + textBox1.Text;
    cmd.CommandType = CommandType.Text;

    if (dr.Read()) // C#
    {
        label1.Text = dr["dname"].ToString();
                   // or use dr.GetOracleString(0).ToString()
    }
}
catch (Exception ex) // catches any error
{
    MessageBox.Show(ex.Message.ToString());
}
finally
{
    // In a real application, put cleanup code here.
}

Although this approach will gracefully capture any errors in attempting to get data from the database, it is not user friendly. For example, look at the following message displayed when the database is unavailable:

An ORA-12545 is quite meaningful for an Oracle DBA or developer, but not for an end user. A better solution is to add an additional Catch statement to trap for the most common database errors and provide user-friendly messages.

Catch ex As OracleException ' catches only Oracle errors
    Select Case ex.Number
        Case 1
            MessageBox.Show("Error attempting to insert duplicate data.")
        Case 12545
            MessageBox.Show("The database is unavailable.")
        Case Else
            MessageBox.Show("Database error: " + ex.Message.ToString())
    End Select
Catch ex As Exception ' catches any error
    MessageBox.Show(ex.Message.ToString())

catch (OracleException ex) // catches only Oracle errors
{
    switch (ex.Number)
    {
        case 1:
            MessageBox.Show("Error attempting to insert duplicate data.");
            break;
        case 12545:
            MessageBox.Show("The database is unavailable.");
            break;
        default:
            MessageBox.Show("Database error: " + ex.Message.ToString());
            break;
    }
}
catch (Exception ex) // catches any error not previously caught
{
    MessageBox.Show(ex.Message.ToString());
}

Notice the two Catch statements in the code sample above. If there aren't any Oracle errors to catch, the first statement branch is skipped, leaving any other non-Oracle error to be caught by the second statement. Catch statements must be ordered in the code from most specific to most general. After implementing the user-friendly exception handling code, the ORA-12545 error message appears as follows:

The Finally code block is always executed regardless of whether or not an error occurred. It is where cleanup code belongs. If you don't use Using or using, you should dispose your connection and other objects in the Finally code block.

Retrieving Multiple Values Using a DataReader

So far our examples have only showed how to retrieve a single value. An OracleDataReader can retrieve values for multiple columns and multiple rows. First consider a multiple column, single row query:

select deptno, dname, loc from dept where deptno = 10

To obtain the values of the columns, either zero-based ordinals or column names can be used. Ordinals are relative to the order in the query. Thus, the LOC column's value can be retrieved in Visual Basic by using either dr.Item(2) or dr.Item("loc").

Here is a code snippet that concatenates the DNAME and LOC columns from the previous query:

Label1.Text = "The " + dr.Item("dname") + " department is in " + dr.Item("loc") ' VB

label1.Text = "The " + dr["dname"].ToString() + " department is in " +
              dr["loc"].ToString();  // C#

Now consider a query that returns multiple rows:

select deptno, dname, loc from dept

To process multiple rows returned from an OracleDataReader, some type of looping construct is needed. Furthermore, a control that can display multiple rows is desirable. An OracleDataReader is a forward-only, read-only cursor, so it can't be bound to an updateable or fully scrollable control such as a Windows Forms DataGrid control. An OracleDataReader is compatible with a ListBox control, as the following code snippet illustrates:

While dr.Read() ' Visual Basic
   ListBox1.Items.Add("The " + dr.Item("dname") + " department is in " + dr.Item("loc"))
End While

while (dr.Read()) // C#
{
    listBox1.Items.Add("The " + dr["dname"].ToString() + " department is in " +
                       dr["loc"].ToString());
}

Lab 3 (Retrieve Multiple Columns and Rows with an OracleDataReader) highlights some of these concepts.

Building and Running on x64

When running Visual Studio 2008 on an x64 operating system, the Active solution platform defaults to Any CPU. Change that to x86 before building your project.

Conclusion

This article has introduced you to the process of accessing Oracle databases using .NET programming languages. You should now have the capability to connect to the database and retrieve multiple columns and rows.

John Paul Cook

In this article, I’ll build a .NET application with Oracle Database and take you step by step through the development lifecycle. Along the way, you will learn how to

• Create users and roles and grant privileges to them
• Import tables and table data from Microsoft Excel spreadsheets (and many third-party databases)
• Automatically generate .NET code for an ASP.NET Web application
• Use Microsoft Query Builder to design SQL
• Generate a SQL script for all the Oracle schema objects your application uses
• Check your application and related SQL scripts into source control from Visual Studio

I’ll also touch on other aspects of the development lifecycle, including PL/SQL debugging and performance tuning.

Setup

To follow along with the steps in this article, you will need the following:

• Oracle9i Database Release 9.2 or later (SYSDBA privileges are required for a few steps)
• Oracle Developer Tools for Visual Studio Release 11.1.0.7.10 (beta) or later
• Microsoft Visual Studio 2008 or Visual Studio 2005
• A source control system with a plug-in for Visual Studio, such as Microsoft SourceSafe, Team Foundation source control, or Subversion

To connect to Oracle Database from Visual Studio, create a connection in Server Explorer. (If Server Explorer is not yet visible, select View -> Server Explorer from the main menu.) Now create the new connection in Data Connections, the top-level node of Server Explorer. Right-click Data Connections, and select Add Connection. In the dialog box that appears, confirm that Oracle Database (Oracle ODP.NET) appears in the Data source field. If you do not see Oracle Database (Oracle ODP.NET), click the Change button and select Oracle Data Provider for .NET from the list of providers. Select the database you want to connect to from the Datasource name list. Click Use a specific user name and password. In the User name field, enter SYS. In the Password field, enter the password for SYS, and ensure that Role is set to SYSDBA. Click Test connection to verify that you can connect, and click OK to complete the connection setup.

Creating a New User with User Designer

Now create an Oracle Database user that you will use during development. In Server Explorer, expand the new SYS connection you just created. You should see two child nodes: Schemas and Roles. Right-click Schemas, and choose New User from the context menu. This will launch User Designer.

I’m creating a user named CSHAY, so in User Designer, for User name, I enter CSHAY (see Figure 1). For Profile I leave the “DEFAULT” value, and for Authentication I select Password. For Password and Confirm password, I enter my chosen password. In the Tablespaces section, I select the location of the default and temporary tablespaces for the CSHAY user. When I installed Oracle Database earlier, I let the Oracle installer create a database for me, so for the default tablespace, I select the USERS tablespace, and for the temporary tablespace, I choose TEMP. Finally, I click Save, which will create my new user account. The SQL that creates the new user account will appear in the output window in Visual Studio.

Figure 1: Creating a user in User Designer

Granting Privileges to the New User Account

Before you can do anything with this new user, you will need to provide some basic privileges. Specifically, you will grant the CONNECT and RESOURCE roles. To do this in Server Explorer, first right-click the SYS connection node and choose Privileges from the context menu. In the Grant/Revoke Privileges dialog box that appears, set Object Type to Role. Select User, and then select CSHAY from the list of users. At the bottom of the dialog box, there will be a list of roles. Select both the CONNECT and the RESOURCE roles, and then click Apply.

In Server Explorer, again right-click the SYS connection node and choose Privileges to reopen the Grant/Revoke Privileges dialog box. This time set Object Type to System Privileges. Select User, and then select CSHAY from the list of users. At the bottom of the dialog box will be a list of privileges. Select the CREATE ROLE privilege, and click Apply. Finally, click OK to dismiss the dialog box.

Now connect to Oracle Database, using the new CSHAY user in Server Explorer. Right-click Data Connections, and select Add Connection. Follow the same steps to connect as CSHAY that you used to connect as SYS, except set Role to Default.

Importing Tables and Table Data

Now you need some tables and table data for the application to use. There are several ways you can achieve this. If you already have a SQL script, you can run it by choosing Tools -> Run SQL Plus Script from the main menu. Or you can create the tables and table data from scratch, by using the table designer and the data window. Additionally, you can use the Import Table Wizard to import tables and table data from any datasource listed in Server Explorer that is using a data provider for .NET that supports ADO.NET 2.0. This could include any other Oracle Database instance, a Microsoft SQL Server database, Microsoft Access, a Microsoft Excel spreadsheet, or many other datasources.

For this article, you will import data from two tables contained within the EMP_DEPT.xls spreadsheet. Download this data via the link in the Next Steps box at the end of this article.

First, connect to the EMP_DEPT.xls spreadsheet in Server Explorer. Right-click Data Connections and select Add Connection. In the dialog box that appears, click the Change button and select <other> from the list. In the Data Provider list, select .NET Framework Data Provider for OLEDB and then click OK. In Server Explorer, right-click Data Connections and select Add Connection, and in the dialog box, under OLEDB provider, select Microsoft Jet 4.0 OLEDB Provider. (Note that if you wanted to use the new Excel 12.0 .xlsx spreadsheet format, you would need to select Microsoft Office 12.0 Access Database Engine OLEDB Provider.) In the Server or File name field, enter the full path to EMP_DEPT.xls, and click the Advanced button, which will open a property sheet. For the Extended Properties property, enter Excel 8.0;HDR=YES. (If you were using the Excel 12.0 .xlsx format, you would enter Excel 12.0;HDR=YES.) Click OK to close the property sheet, click Test to test the connection, and click OK once more to close the Add Connection dialog box.

Now import the data from the connected spreadsheet. Right-click the CSHAY connection node, and select Import Table. This will start the Import Table Wizard. Click Next until you see the Choose Data Source Connection screen. For the data connection source, choose the emp_dept.xls connection. Click Next to go to the Select Tables to Import screen. Under Source Table, click the check boxes next to both DEPARTMENTS$ and EMPLOYEES$. Click each destination table name, and then edit each name to remove the dollar sign at the end (see Figure 2). The Import Data check box is checked by default, which is what you want.

Figure 2: Import Table Wizard: Renaming the destination table

Click Next to go to the Customize Columns Settings screen (see Figure 3). For each column of type BINARY_DOUBLE, highlight the row, and in the Data Type list, choose NUMBER. For EMPLOYEES.EMPLOYEE_ID, uncheck the Allows NULL check box and then check the Primary Key check box. Do the same for DEPARTMENTS .DEPARTMENT_ID. (Note that you will need to use the Select a Table list at the top of the screen to switch between the two tables.) Click Finish to import the data.

Figure 3: Import Table Wizard: Choosing the destination column datatype

After the data has been successfully imported, click OK and then go to Server Explorer, right-click the CSHAY connection, and select Refresh. Navigate to the Tables node to view the newly imported tables.

Automatically Generating the .NET Code for a Web Application

Now, taking advantage of Visual Studio’s automatic .NET code generation features, create an ASP.NET Web application to display the data you just imported into Oracle Database. You could just as easily create a client/server Winform application or a Microsoft Office application by using similar steps.

From the Visual Studio main menu, select File -> New Project. For Visual C# Project Type select Web, and then select the ASP.NET Web Application template. Click the Design button, below the HTML code window. If the toolbox is not already visible, choose View -> Toolbox from the main menu.

Scroll down to the Data section of the toolbox, and drag and drop a GridView control onto the design surface. The GridView Tasks window should immediately open, but if it does not, click the small > icon to open it. From the Choose Data Source list, select :<New Data Source>. This will open the Data Source Configuration Wizard to the Choose a Data Source Type screen. Select the Database icon, and then click OK. On the Choose Your Data Connection screen (the next screen), select CSHAY for the data connection, and click Next. On the Save a Connection String to the Application Configuration File screen, accept the defaults and click Next.

On the Configure the Select Statement screen, select Specify a Custom SQL Statement and click Next. On the Define Custom Statements screen, click the Query Builder button. When Microsoft Query Builder launches and the Add Table dialog box appears, select the DEPARTMENTS and EMPLOYEES tables and click the Add button. In the top section of Query Builder, you will see both tables automatically joined by DEPARTMENT_ID (see Figure 4).

Figure 4: Microsoft Query Builder

Now you need to decide which columns to select in your query. In the EMPLOYEES table, select the EMPLOYEE_ID, FIRST_NAME, LAST_NAME, and SALARY columns. In the DEPARTMENTS table, select the DEPARTMENT_NAME column. In the second pane from the top, order the column list by dragging and dropping so that EMPLOYEE_ID is the first Select list item and DEPARTMENT_NAME is last. Click the Execute Query button to test the query. Click OK to finish and return to the Define Custom Statements screen of the Data Source Configuration Wizard. Click Next; test the query again (if you wish), by clicking the Test Query button; and then click Finish.

From the main menu, select Debug -> Start Without Debugging, which will open your Web browser and display your running application (see Figure 5).

Figure 5: The application running in a Web browser

Creating an Oracle Database Project

You will want to store the SQL scripts for the Oracle Database schema objects the application uses and eventually check them into source control along with the application. This will allow other developers who obtain the application code to also check out and run the SQL scripts to create the Oracle schema objects the application requires.

Before you store the SQL and application code, create a project location for the code. To add an Oracle Database project to the Visual Studio solution, first right-click the topmost node in Solution Explorer and select Add -> New Project from the context menu. Under Project Types, select Other Project Types and then Database, and then select the Oracle Database Project template. When asked to select a database reference to be stored with the project, choose the CSHAY connection and click OK.

Creating a Role for the Application

You may want to create a role that represents the privileges required to access the database objects the application uses. Using Oracle roles is a good way to ensure that application users have the correct privileges. Also, if your application later requires additional privileges, modifying a single role is much easier than making new privilege grants to each individual user. This article’s sample application, for example, will need access to the EMPLOYEES and DEPARTMENTS tables.

To create the application user role, right-click the Roles node under the CSHAY connection, and select New Role from the context menu. Enter EMPDEPT_WEBAPP in the Role Name field, and then click Save.

Next, grant privileges to the role you just created. Right-click the EMPDEPT_WEBAPP node under the Roles node, and select Privileges from the context menu. When the Privilege Wizard launches, set Object Type to Table (see Figure 6). The Schema field should be set to CSHAY. Select Grant/Revoke privileges to a user/role on one or more database object(s), and then in the Object Name(s) list, select both DEPARTMENTS and EMPLOYEES (by holding down the Shift key while you click). Select Role, and then select EMPDEPT_WEBAPP from the list of roles.

Figure 6: Granting permissions on tables to the EMPDEPT_WEBAPP role

At the bottom of the dialog box, there will be a list of privileges. Select the DELETE, INSERT, SELECT, and UPDATE privileges. Click the Preview SQL button, and then click Add to Project. This will create a SQL script that contains the GRANT statements and will add it to the Oracle Database project. (You will use these GRANT statements in the next section.) Click OK to dismiss the Preview SQL window, and then click the Apply button to execute the SQL needed to grant the privileges. Then click OK to dismiss the dialog box.

Generating SQL Scripts

Now generate the SQL scripts for the tables the application uses, so that you can check them into source control along with the application. In Server Explorer, under the CSHAY node, while holding down the Control key, select the DEPARTMENTS table, the EMPLOYEES table, and the EMPDEPT_WEBAPP role. With all three selected, right-click and select Generate Create Script to Project. Provide a script name, and click OK. After the script is added, the Oracle SQL script editor will open and display the script (see Figure 7).

Figure 7: The Oracle SQL script editor (left) and project with source control menu items (right)

Under Solution Explorer, in the Security -> Permissions folder, open the script containing GRANT statements that you created earlier. Copy these GRANT statements, and paste them at the end of the just-generated SQL script. Save this script. You can now delete the GRANT script from the Permissions folder. Although it is not necessary to merge these two scripts, it is generally simpler to use one deployment SQL script for each application in source control.

Adding Application and SQL Scripts into Source Control

The first time you use source control in Visual Studio, you will need to enable it. From the main menu, select Tools -> Options, and then select Source Control. Under Current Source Control Plug-in, select the plug-in corresponding to your source control system. If you don’t see it listed here, you will need to obtain it from the vendor and install it.

To add your solution into source control, right-click the solution name in Solution Explorer and select Add Solution to Source Control. After the solution is added to source control, new icons will appear next to the filenames and source control menu items such as Check Out for Edit will be available (see Figure 7). When users check out SQL scripts from source control, they will be able to run them (using a built-in SQL*Plus execution engine) by right-clicking and selecting Run from the context menu. This will ensure that their database schema matches the one required by the application.

Debugging Your Application’s PL/SQL

Although this application doesn’t use PL/SQL, note that you can use all the powerful features of the Visual Studio debugger with your stored functions or procedures. Debugging the PL/SQL your application uses is a very important part of the application lifecycle that was covered extensively in an earlier Oracle Magazine article (“Debugging PL/SQL from .NET”).

Performance Tuning

Now you are ready to tune the application and its use of Oracle Database. The main performance tuning feature provided by Oracle Developer Tools for Visual Studio is Oracle Performance Analyzer. You can launch it by clicking a SYSDBA connection in Server Explorer and choosing Oracle Performance Analyzer from the context menu. It monitors the use of the database under load and provides performance-improving recommendations, some of which can be implemented automatically. I’ll be deep-diving into Oracle Performance Analyzer and performance tuning tricks in an upcoming article.

Christian Shay