Visual C# 2010 Recipes solution_4

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Visual C# 2010 Recipes solution_4 CHAPTER 9 ■ DATABASE ACCESS The Code The following example demonstrates how to retrieve results as XML using the FOR XML clause and the ExecuteXmlReader method: using System; using System.Xml; using System.Data; using System.Data.SqlClient; namespace Apress.VisualCSharpRecipes.Chapter09 { class Recipe09_08 { public static void ConnectedExample() { // Create a new SqlConnection object. using (SqlConnection con = new SqlConnection()) { // Configure the SqlConnection objects connection string. con.ConnectionString = @Data Source = .sqlexpress; + Database = Northwind; Integrated Security=SSPI; // Create and configure a new command that includes the // FOR XML AUTO clause. using (SqlCommand com = con.CreateCommand()) { com.CommandType = CommandType.Text; com.CommandText = SELECT CustomerID, CompanyName + FROM Customers FOR XML AUTO; // Open the database connection. con.Open(); // Execute the command and retrieve an XmlReader to access // the results. using (XmlReader reader = com.ExecuteXmlReader()) { while (reader.Read()) { Console.Write(Element: + reader.Name); if (reader.HasAttributes) { for (int i = 0; i < reader.AttributeCount; i++) { reader.MoveToAttribute(i); Console.Write( {0}: {1}, reader.Name, reader.Value); }450 CHAPTER 9 ■ DATABASE ACCESS // Move the XmlReader back to the element node. reader.MoveToElement(); Console.WriteLine(Environment.NewLine); } } } } }}public static void DisconnectedExample(){ XmlDocument doc = new XmlDocument(); // Create a new SqlConnection object. using (SqlConnection con = new SqlConnection()) { // Configure the SqlConnection objects connection string. con.ConnectionString = @Data Source = .sqlexpress; + Database = Northwind; Integrated Security=SSPI; // Create and configure a new command that includes the // FOR XML AUTO clause. SqlCommand com = con.CreateCommand(); com.CommandType = CommandType.Text; com.CommandText = SELECT CustomerID, CompanyName FROM Customers FOR XML AUTO; // Open the database connection. con.Open(); // Load the XML data into the XmlDocument. Must first create a // root element into which to place each result row element. XmlReader reader = com.ExecuteXmlReader(); doc.LoadXml(); // Create an XmlNode from the next XML element read from the // reader. XmlNode newNode = doc.ReadNode(reader); while (newNode != null) { doc.DocumentElement.AppendChild(newNode); newNode = doc.ReadNode(reader); } } // Process the disconnected XmlDocument. Console.WriteLine(doc.OuterXml);} 451 CHAPTER 9 ■ DATABASE ACCESS public static void Main(string[] args) { ConnectedExample(); Console.WriteLine(Environment.NewLine); DisconnectedExample(); Console.WriteLine(Environment.NewLine); // Wait to continue. Console.WriteLine(Environment.NewLine); Console.WriteLine(Main method complete. Press Enter.); Console.ReadLine(); } } } 9-9. Perform Asynchronous Database Operations Against SQL Server Problem You need to execute a query or command against a SQL Server database as a background task while your application continues with other processing. Solution Use the BeginExec ...