HOW TO: Call SQL Server Stored Procedures in ASP.NET by Using Visual J# .NET (320622)

SUMMARY

This article demonstrates how to use ASP.NET and ADO.NET with Visual J# .NET to create and to call a Microsoft SQL Server stored procedure with an input parameter and an output parameter.

The code sample in this article first checks whether the stored procedure that you create exists in the database. If the stored procedure does not exist, the code creates a stored procedure that takes one parameter to search the Authors table based on the last name and returns the matching rows and number of rows that are returned in an output parameter.

This article also demonstrates how to create a Web Form that provides a simple user interface. The Web Form contains the following items:

A text box in which the user types the search condition.
A DataGrid control that displays the search results.
A Label control that displays the number of returned records.
A Button control that calls the stored procedure when the button is clicked.

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Requirements

The following list outlines the recommended hardware, software, network infrastructure, and service packs that are required:

Microsoft SQL Server version 7.0 or later
Microsoft Visual Studio .NET
Microsoft Visual J# .NET
Permissions to create the stored procedure in the database

This article assumes that you are familiar with the following topics:

SQL Server stored procedures

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Create an ASP.NET Project and Add Controls

In this section, you create an ASP.NET project and build the basic user interface. Note that these steps use Microsoft Visual J# .NET code. To create the project, follow these steps:

Click Start, point to Programs, point to Microsoft Visual Studio .NET, and then click Microsoft Visual Studio .NET.
On the Visual Studio .NET Start page, click New Project.
In the New Project dialog box, click Visual J# Projects under Project Types, and then click ASP.NET Web Application under Templates.
In the Location box, type the URL for your Web server and a name for your Web application (for example, type http://localhost/jsGetAuthors), and then click OK.
Add the following server controls to the Web Form, and set the properties as they are listed in the table:
Control ID Property Text Property
Label lblLastName Type the Author's Last Name:
TextBox txtLastName %
Button btnGetAuthors Get Authors
Label lblRowCount (Row Count)
Drag a DataGrid server control from the toolbox to the Web Form, and then set the ID property to GrdAuthors.
Right-click the grid, and then click Autoformat.
Click Professional 1 for the scheme, and then click OK.

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Create the GetAuthorsByLastName Stored Procedure

Use the following Transact-SQL code to create the GetAuthorsByLastName stored procedure. Note that this procedure is created in the Visual J# .NET code below even if it is not manually created at this point):

Create Procedure GetAuthorsByLastName (@au_lname varchar(40), @RowCount int output)  
as 

select * from authors where au_lname like @au_lname; 

/* @@ROWCOUNT returns the number of rows that are affected by the last statement. */ 
select @RowCount=@@ROWCOUNT

This code includes two parameters: @au_lname and @RowCount. The @au_lname parameter is an input parameter that obtains the search string to perform a "like" search in the Authors table. The @RowCount parameter is an output parameter that uses the @@ROWCOUNT variable to obtain the affected rows.

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Create and Run the Stored Procedure

To access SQL Server databases, you must import the System.Data.SqlClient namespace, which provides new objects such as the SqlDataReader and the SqlDataAdapter objects. You can use SqlDataReader to read a forward-only stream of rows from a SQL Server database. DataAdapter represents a set of data commands and a database connection that you can use to fill the DataSet object and to update a SQL Server database.

ADO.NET also introduces the DataSet object, which is a memory-resident representation of data that provides a consistent, relational programming model regardless of the data source. The code in this section uses all of these objects.

Double-click an empty space on the Web Form to view the Visual J# .NET code that is associated with the Web Form.
Add the following code just after the package statement, which appears at the top of the Code window:
```
import System.Data.SqlClient.*;
					
```

To make sure that the stored procedure exists and to create a new stored procedure, use a SqlCommand object with a SqlDataReader object. You can use SqlCommand to run any SQL commands against the database. Then call the ExecuteReader method of SqlCommand to return SqlDataReader, which contains matching rows for your query.

Add the following code in the Page_Load event of the Web Form:

// Put user code to initialize the page here.
// The code inside the If statement is skipped when you resubmit the page.
if ( !(get_IsPostBack()))
{
	//Create a Connection object.
	SqlConnection MyConnection = new  SqlConnection("server=(local);database=pubs;Trusted_Connection=yes");
	//Create a Command object, and then set the connection.
	//The following SQL statements check whether a GetAuthorsByLastName stored procedure already exists.
SqlCommand MyCommand = new SqlCommand("if object_id('northwind..GetAuthorsByLastName') is not null" + " begin" + 
			" if objectproperty(object_id('northwind..GetAuthorsByLastName'), 'IsProcedure')= 1" + 
				" select object_id('northwind..GetAuthorsByLastName')" + 
			" else" + " return" + " end" + 
			" else" + " return", MyConnection);
	//Set the command type that you will run.
	MyCommand.set_CommandType(CommandType.Text);
	//Open the connection.
	MyCommand.get_Connection().Open();
	//Run the SQL statement, and then get the returned rows to a DataReader.
	SqlDataReader MyDataReader = MyCommand.ExecuteReader();

	//If any rows are retuned, the stored procedure that you are trying to create already exists. 
	//Therefore, try to create the stored procedure only if it does not exist.
	if (!MyDataReader.Read()) 
	{
		MyCommand.set_CommandText("create procedure GetAuthorsByLastName (@au_lname varchar(40), @RowCount int output)" +
					" as select * from authors where au_lname like @au_lname; select @RowCount=@@ROWCOUNT");
		MyDataReader.Close();
		MyCommand.ExecuteNonQuery();
	}
	else
		MyDataReader.Close();
	
	//Dispose of the Command object.
	MyCommand.Dispose(); 
	//Close the connection.
	MyConnection.Close();
}

Change the connection string in the code to connect to your server that is running SQL Server.

Call the stored procedure in the Click event of the btnGetAuthors button, and then use the SqlDataAdapter object to run your stored procedure. You must create parameters for the stored procedure and append it to the Parameters collection of the SqlDataAdapter object.

Double-click the btnGetAuthors button in Design view, and then add the following code to the Click event:

private void btnGetAuthors_Click (System.Object sender, System.EventArgs e)
{	
	//Create a connection to the SQL Server.
	SqlConnection MyConnection = new SqlConnection("server=(local);database=pubs;Trusted_Connection=yes");
	//Create a DataAdapter, and then provide the name of the stored procedure.
	SqlDataAdapter MyDataAdapter = new SqlDataAdapter("GetAuthorsByLastName", MyConnection);
	//Set the command type as StoredProcedure.
	MyDataAdapter.get_SelectCommand().set_CommandType(CommandType.StoredProcedure);
	//Get the parameter collection from the select command of the DataAdapter object.
	SqlParameterCollection ParamColl = MyDataAdapter.get_SelectCommand().get_Parameters();
	//Add a parameter to Parameters collection, and then specify its name, type and size.
	ParamColl.Add("@au_lname",SqlDbType.VarChar,40); 
	//Assign the search value to the parameter.
	ParamColl.get_Item("@au_lname").set_Value((System.String)txtLastName.get_Text()); 
	//Add an output parameter to Parameters collection, and then specify its name, type and size.
	ParamColl.Add("@RowCount",SqlDbType.Int, 4);
	//Set the direction for the parameter. This parameter returns the Rows returned.
	ParamColl.get_Item("@RowCount").set_Direction(ParameterDirection.Output);

	//Create a new DataSet to hold the records.
	DataSet DS = new DataSet();
	//Fill the DataSet with the rows that are returned.
	MyDataAdapter.Fill(DS, "AuthorsByLastName");

	//Get the number of rows that are returned, and then assign it to the Label control.
	lblRowCount.set_Text(ParamColl.get_Item(1).get_Value() + " Rows Found!");

	//Set the data source for the DataGrid as the DataSet that holds the rows.
	GrdAuthors.set_DataSource(DS);
	//Set the data member for the DataGrid as the AuthorsByLastName DataTable.
	GrdAuthors.set_DataMember("AuthorsByLastName");

	//Bind the DataSet to DataGrid. NOTE: If you do not call this method, the DataGrid is not displayed!
	GrdAuthors.DataBind();

	//Dispose of the DataAdapter.
	MyDataAdapter.Dispose();
	//Close the connection.
	MyConnection.Close();
}

Change the connection string in the code to connect to your server that is running SQL Server.
In Solution Explorer, right-click the .aspx page, and then click Set as Start Page.
Save the project, and then click Start in Visual Studio .NET. Notice that the project is compiled and that the default page runs.
Type the author's last name in the text box, and then click Get Author. Notice that the stored procedure is called and that the returned rows populate the DataGrid.

You can provide SQL Server-type search strings such as G%, which returns all of the authors by last names that start with the letter "G."

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Troubleshooting

If you cannot connect to the database, make sure that the ConnectionString properly points to the server that is running SQL Server.
If you can connect to the database, but if you experience problems when you try to create the stored procedure, make sure that you have the correct permissions to create stored procedures in the database to which you are connecting.

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HOW TO: Call SQL Server Stored Procedures in ASP.NET by Using Visual J# .NET (320622)

IN THIS TASK

SUMMARY

Requirements

Create an ASP.NET Project and Add Controls

Create the GetAuthorsByLastName Stored Procedure

Create and Run the Stored Procedure

Troubleshooting