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This chapter is from the book

Apply Your Knowledge

Exercises

2.1 - Compiling XPath Expressions

The .NET Framework developers invested a lot of effort in finding ways to make code more efficient. One performance enhancement in evaluating XPath expressions is the capability to precompile an expression for reuse. This exercise shows you how to use the Compile() method of the XPathNavigator class to create a precompiled XPath expression, represented as an XPathExpression object.

Estimated Time: 15 minutes.

  1. Create a new Visual C# .NET project to use for the exercises in this chapter.

  2. Add a new XML file to the project. Name the new file Books1.xml. Modify the XML for Books1.xml as follows:

    <?xml version="1.0" encoding="UTF-8"?>
    <Books>
      <Book Pages="1088">
        <Author>Delaney, Kalen</Author>
        <Title>
          Inside Microsoft SQL Server 2000
        </Title>
        <Publisher>Microsoft Press
        </Publisher>
      </Book>
      <Book Pages="997">
        <Author>Burton, Kevin</Author>
        <Title>.NET Common Language Runtime
        </Title>
        <Publisher>Sams</Publisher>
      </Book>
      <Book Pages="392">
        <Author>Cooper, James W.</Author>
        <Title>C# Design Patterns</Title>
        <Publisher>Addison Wesley
        </Publisher>
      </Book>
    </Books>
  3. Add a new XML file to the project. Name the new file Books2.xml. Modify the XML for Books2.xml as follows:

    <?xml version="1.0" encoding="UTF-8" ?>
    <Books>
      <Book Pages="792">
        <Author>LaMacchia, Brian A.
        </Author>
        <Title>.NET Framework Security
        </Title>
        <Publisher>Addison Wesley
        </Publisher>
      </Book>
      <Book Pages="383">
        <Author>Bischof Brian</Author>
        <Title>The .NET Languages:
         A Quick Translation Guide</Title>
        <Publisher>Apress</Publisher>
      </Book>
      <Book Pages="196">
        <Author>Simpson, John E.</Author>
        <Title>XPath and XPointer</Title>
        <Publisher>O'Reilly</Publisher>
      </Book>
    </Books>
  4. Add a new form to the project. Name the new form Exercise2_1.cs.

  5. Add a Label control, a TextBox control (txtXPath), a Button control (btnEvaluate), and a ListBox control (lbNodes) to the form.

  6. Switch to code view and add the following using directive:

  7. using System.Xml.XPath;

  8. Double-click the Button control and add code to handle the button's Click event:

    private void btnEvaluate_Click(
      object sender, System.EventArgs e)
    {
      // Load the Books1.xml file
      XPathDocument xpd1 =
        new XPathDocument(
        @"..\..\Books1.xml");
      // Get the associated navigator
      XPathNavigator xpn1 =
        xpd1.CreateNavigator();
      // Precompile an XPath expression
      XPathExpression xpe =
        xpn1.Compile(txtXPath.Text);
      // Retrieve nodes to match
      // the expression
      XPathNodeIterator xpni =
        xpn1.Select(xpe);
      // And dump the results
      lbNodes.Items.Clear();
      lbNodes.Items.Add(
        "Results from Books1.xml:");
      // Load the Books1.xml file
    
      while(xpni.MoveNext())
      {
        lbNodes.Items.Add(" " +
         xpni.Current.NodeType.ToString() +
         ": " + xpni.Current.Name + " = " +
         xpni.Current.Value);
      }
    
      // Now get the second document
      XPathDocument xpd2 =
        new XPathDocument(
        @"..\..\Books2.xml");
      // Get the associated navigator
      XPathNavigator xpn2 =
        xpd2.CreateNavigator();
      // Retrieve nodes to match
      // the expression
      // Reuse the precompiled expression
      xpni = xpn2.Select(xpe);
      // And dump the results
      lbNodes.Items.Add(
        "Results from Books2.xml:");
      while (xpni.MoveNext())
      {
        lbNodes.Items.Add(" " +
        xpni.Current.NodeType.ToString() +
        ": " + xpni.Current.Name + " = " +
          xpni.Current.Value);
      }
    }
  9. Insert the Main() method to launch the form. Set the form as the startup form for the project.

  10. Run the project. Enter an XPath expression and click the button. The code precompiles the expression and then uses the precompiled version to select nodes from each of the two XML files, as shown in Figure 2.18.

Figure 2.18Figure 2.18 The Compile() method of the XPathNavigator class allows you to create a precompiled XPath expression.

2.2 - Creating DiffGrams

If you'd like to experiment with the DiffGram format, you don't have to create DiffGrams by hand. You can use the WriteXml() method of the DataSet object to create a DiffGram containing all the changes made since the DataSet object was initialized. This exercise walks you through the process of creating a DiffGram.

Estimated Time: 15 minutes.

  1. Add a new form to the project. Name the new form Exercise2_2.cs.

  2. Add a DataGrid control (dgProducts) and a Button control (btnWriteDiffGram) to the form.

  3. Expand the Server Explorer tree view to show a Data Connection to the Northwind sample database. Drag and drop the connection to the form.

  4. Drag a SaveFileDialog component from the Toolbox and drop it on the form. Set the FileName property of the component to diffgram.xml.

  5. Switch to code view and add the following using directive:

    using System.Data;
    using System.Data.SqlClient;
  6. Add the following DataSet declaration to the class definition:

    DataSet dsProducts = new DataSet();
  7. Double-click the form and add the following code to handle the form's Load event:

    private void Exercise2_2_Load(
      object sender, System.EventArgs e)
    {
      // Create a command to retrieve data
      SqlCommand cmd =
        sqlConnection1.CreateCommand();
      cmd.CommandType = CommandType.Text;
      cmd.CommandText =
        "SELECT * FROM Products " +
        "WHERE CategoryID = 6";
      // Retrieve the data to the DataSet
      SqlDataAdapter da =
        new SqlDataAdapter();
      da.SelectCommand = cmd;
      da.Fill(dsProducts, "Products");
      // Bind it to the user interface
      dgProducts.DataSource = dsProducts;
      dgProducts.DataMember = "Products";
    }
  8. Double-click the button and add the following code to handle the button's Click event:

    private void btnWriteDiffGram_Click(
      object sender, System.EventArgs e)
    {
      // Prompt for a filename
      saveFileDialog1.ShowDialog();
      // Write out the DiffGram
      dsProducts.WriteXml(
        saveFileDialog1.FileName,
        XmlWriteMode.DiffGram);
    }
  9. Insert the Main() method to launch the form. Set the form as the startup form for the project.

  10. Run the project. The form displays records from the Northwind Products table for the selected category ID. Make some changes to the data; you can use the DataGrid to add, edit, or delete records. Click the button and select a name for the DiffGram. Click the Write DiffGram button to create the DiffGram. Open the new DiffGram in a text editor and inspect it to see how your changes are represented.

2.3 - Using XPath with Relational Data

By combining an XML-synchronized DataSet object with an XPath expression, you can use XPath to select information from a relational database. This exercise shows you how you can use a DataSet object, an XmlDataDocument object, and an XPathNavigator object together.

Estimated Time: 25 minutes.

  1. Add a new form to the project. Name the new form Exercise2_3.cs.

  2. Add two Label controls, two TextBox controls (txtSQLStatement and txtXPath), two Button controls (btnCreateDataSet and btnSelectNodes), and a ListBox control (lbNodes) to the form.

  3. Expand the Server Explorer tree view to show a data connection to the Northwind sample database. Drag and drop the connection to the form.

  4. Switch to code view and add the following using directives:

    using System.Data;
    using System.Data.SqlClient;
    using System.Xml;
    using System.Xml.XPath;
  5. Add the following code to the class definition:

    DataSet ds;
    XmlDataDocument xdd;
  6. Double-click the Create DataSet button and enter code to load a DataSet object and an XmlDataDocument object:

    private void btnCreateDataSet_Click(
      object sender, System.EventArgs e)
    {
      // Create a command to retrieve data
      SqlCommand cmd =
        sqlConnection1.CreateCommand();
      cmd.CommandType = CommandType.Text;
      cmd.CommandText = txtSQLStatement.Text;
      // Retrieve the data to the DataSet
      SqlDataAdapter da =
        new SqlDataAdapter();
      da.SelectCommand = cmd;
      ds = new DataSet();
      da.Fill(ds, "Table1");
      // Retrieve the XML form of the Dataset
      xdd = new XmlDataDocument(ds);
    }
  7. Double-click the Select Nodes button and enter code to evaluate the XPath expression:

    private void btnSelectNodes_Click(
      object sender, System.EventArgs e)
    {
      // Get the associated navigator
      XPathNavigator xpn =
        xdd.CreateNavigator();
      // Retrieve nodes to match
      // the expression
      XPathNodeIterator xpni =
        xpn.Select(txtXPath.Text);
      // And dump the results
      lbNodes.Items.Clear();
      while (xpni.MoveNext())
      {
        lbNodes.Items.Add(
          xpni.Current.NodeType.ToString()
          + ": " + xpni.Current.Name +
          " = " + xpni.Current.Value);
      }
    }
  8. Insert the Main() method to launch the form. Set the form as the startup form for the project.

  9. Run the project. Enter a SQL Statement that retrieves rows and click the first button. Then enter an XPath expression and click the second button. You'll see the XPath query results as a set of XML nodes, as shown in Figure 2.19.

Figure 2.19Figure 2.19 You can use XPath with an XmlDataDocument object.

Review Questions

  1. How are XML elements and attributes represented in the DOM?

  2. When should you use an XmlTextReader object by itself rather than with an XmlDocument object?

  3. Explain three ways to synchronize an XmlDataDocument object with a DataSet object.

  4. Why should you use an explicit path rather than a documentwide wildcard in an XPath expression?

  5. What is the difference between the XPath expressions /Customers/Customer/Order[1] and (/Customers/Customer/Order)[1]?

  6. How can you instantiate an XPathNavigator object?

  7. What options are there for validating an XML file with the XmlValidatingReader object?

  8. What are the three main variants of the FOR XML clause in T-SQL?

  9. How can you generate schema information with the FOR XML clause in T-SQL?

  10. What data operations can be represented in a DiffGram?

Exam Questions

  1. Your application contains an XML file, Orders.xml, with the following content:

    <?xml version="1.0" encoding="utf-8" ?>
    <Orders>
     <Order OrderID="1">
      <OrderDate>1/1/2003</OrderDate>
     </Order>
     <Order OrderID="2">
      <OrderDate>1/2/2003</OrderDate>
     </Order>
     <Order OrderID="3">
      <OrderDate>1/3/2003</OrderDate>
     </Order>
    </Orders>

    Your application also contains a form with a Button control named btnProcess and a ListBox control named lbNodes. The Click event handler for the Button control has this code:

    private void btnProcess_Click(
      object sender, System.EventArgs e)
    {
      XmlTextReader xtr = new
        XmlTextReader(@"..\..\Orders.xml");
      while(xtr.Read())
      {
        if ((xtr.NodeType ==
            XmlNodeType.Attribute)
          || (xtr.NodeType ==
            XmlNodeType.Element)
          || (xtr.NodeType ==
            XmlNodeType.Text))
        {
          if(xtr.HasValue)
           lbNodes.Items.Add(xtr.Value);
        }
      }
      xtr.Close();
    }

    What will be the contents of the ListBox control after you click the button?

    1. 1
      1/1/2003
      2
      1/2/2003
      3
      1/3/2003
    2. 1
      2
      3
    3. Orders
      Order
      1/1/2003
      Order
      1/2/2003
      Order
      1/3/2003
    4. 1/1/2003
      1/2/2003
      1/3/2003
  2. Your application contains the following XML file:

    <?xml version="1.0" encoding="utf-8" ?>
    <Orders>
     <Order OrderID="1">
      <OrderDate>1/1/2003</OrderDate>
     </Order>
     <Order OrderID="2">
      <OrderDate>1/2/2003</OrderDate>
     </Order>
     <Order OrderID="3">
      <OrderDate>1/3/2003</OrderDate>
     </Order>
    </Orders>

    Your application uses the ReadXmlSchema() method of the DataSet object to create a DataSet object with an appropriate schema for this XML file. Which of the following mappings between XML entities and DataSet object entities will this method create?

    1. Orders and Order will become DataTable objects. OrderID will become a DataColumn object. OrderDate will not be mapped.

    2. Orders and Order will become DataTable objects. OrderID and OrderDate will become DataColumn objects.

    3. Orders and Order will become DataTable objects. OrderDate will become a DataColumn. OrderID will not be mapped.

    4. Orders will become a DataTable. Order and OrderDate will become DataColumn objects.

  3. Your application includes an XML file that represents inventory in a warehouse. Each inventory item is identified by 50 different elements. You need to work with 4 of these elements on a DataGrid control. You plan to create a DataSet object containing the appropriate data that can be bound to the DataGrid control. How should you proceed?

    1. Load the XML file into an XmlDocument object. Create a DataSet object containing a single DataTable object with the desired column. Write code that loops through the nodes in the XmlDocument object and that transfers the data from the appropriate nodes to the DataSet object.

    2. Load the XML file into an XmlDataDocument object. Retrieve the DataSet object from the XmlDataDocument object's DataSet property.

    3. Load the XML file into a DataSet object by calling the DataSet object's ReadXml() method.

    4. Create a schema that includes the four required elements. Create a DataSet object from this schema. Create an XmlDataDocument object from the DataSet object. Load the XML document into the XmlDataDocument object.

  4. You use a SqlDataAdapter object to fill a DataSet object with the contents of the Customers table in your database. The CompanyName of the first customer is "Biggs Industries". You synchronize an XmlDataDocument object with the DataSet object. In the DataSet object, you change the CompanyName of the first customer to "Biggs Limited". After that, in the XmlDataDocument, you change the value of the corresponding node to "Biggs Co." When you call the Update() method of the SqlDataAdapter object, what is the effect?

    1. The CompanyName in the database remains "Biggs Industries".

    2. The CompanyName in the database is changed to "Biggs Limited".

    3. The CompanyName in the database is changed to "Biggs Co."

    4. A record locking error is thrown.

  5. Your application contains the following XML file:

    <?xml version="1.0" encoding="utf-8" ?>
    <Customers>
     <Customer>
      <CustomerName>A Company</CustomerName>
      <Orders>
       <Order OrderID="1">
        <OrderDate>1/1/2003</OrderDate>
       </Order>
       <Order OrderID="2">
        <OrderDate>1/2/2003</OrderDate>
       </Order>
      </Orders>
     </Customer>
     <Customer>
      <CustomerName>B Company</CustomerName>
      <Orders>
       <Order OrderID="3">
        <OrderDate>1/2/2003</OrderDate>
       </Order>
       <Order OrderID="4">
        <OrderDate>1/3/2003</OrderDate>
       </Order>
      </Orders>
     </Customer>
     <Customer>
      <CustomerName>C Company</CustomerName>
      <Orders>
       <Order OrderID="5">
        <OrderDate>1/4/2003</OrderDate>
       </Order>
       <Order OrderID="6">
        <OrderDate>1/5/2003</OrderDate>
       </Order>
      </Orders>
     </Customer>
    </Customers>

    Which XPath expression will return the first OrderID for each customer?

    1. /Customers/Customer/Orders/Order/@OrderID[1]

    2. (/Customers/Customer/Orders/Order)[1]/@OrderID

    3. /Customers/Customer/Orders/Order[1]/@OrderID

    4. (/Customers/Customer/Orders/Order/@OrderID)[1]

  6. Your application contains the following XML file:

    <?xml version="1.0" encoding="utf-8" ?>
    <Customers>
     <Customer>
      <CustomerName>A Company</CustomerName>
      <Orders>
       <Order OrderID="1">
        <OrderDate>1/1/2003</OrderDate>
       </Order>
       <Order OrderID="2">
        <OrderDate>1/2/2003</OrderDate>
       </Order>
      </Orders>
     </Customer>
     <Customer>
      <CustomerName>B Company</CustomerName>
      <Orders>
       <Order OrderID="3">
        <OrderDate>1/2/2003</OrderDate>
       </Order>
       <Order OrderID="4">
        <OrderDate>1/3/2003</OrderDate>
       </Order>
      </Orders>
     </Customer>
     <Customer>
      <CustomerName>C Company</CustomerName>
      <Orders>
       <Order OrderID="5">
        <OrderDate>1/4/2003</OrderDate>
       </Order>
       <Order OrderID="6">
        <OrderDate>1/5/2003</OrderDate>
       </Order>
      </Orders>
     </Customer>
    </Customers>

    Which XPath expression will return the CustomerName for all customers who placed an order on 1/3/2003?

    1. /Customers/Customer[./Orders/Order/OrderDate="1/3/2003"]/CustomerName

    2. /Customers/Customer[/Orders/Order/OrderDate="1/3/2003"]/CustomerName

    3. /Customers/Customer[//Orders/Order/OrderDate="1/3/2003"]/CustomerName

    4. /Customers/Customer[Orders/Order/OrderDate="1/3/2003"]/CustomerName

  7. Your application allows the user to perform arbitrary XPath queries on an XML document. The user does not need to be able to alter the document. Which approach will give you the maximum performance for these requirements?

    1. Read the document into an XmlDocument object. Use the CreateNavigator() method of the XmlDocument object to return an XPathNavigator object. Perform your queries by using the XPathNavigator object.

    2. Read the document into an XmlDataDocument object. Use the DataSet property of the XmlDataDocument object to return a DataSet object. Perform your queries by using the DataSet object.

    3. Read the document into an XmlDataDocument object. Use the CreateNavigator() method of the XmlDataDocument object to return an XPathNavigator object. Perform your queries by using the XPathNavigator object.

    4. Read the document into an XPathDocument object. Use the CreateNavigator() method of the XPathDocument object to return an XPathNavigator object. Perform your queries by using the XPathNavigator object.

  8. You are designing an application that will enable the user to explore the structure of an XML file. You need to allow the user to move to the parent node, next node, or first child node from the current node. Which object should you use to implement this requirement?

    1. XPathNavigator

    2. XmlReader

    3. XmlTextReader

    4. XPathExpression

  9. Your XML document has an inline schema. What is the minimum number of errors that this document will generate if you validate it with the XmlValidatingReader class?

    1. 0

    2. 1

    3. 2

    4. 3

  10. You are retrieving customer data from a SQL Server database into an XML document. You want the CustomerName and ContactName columns to be translated into XML elements. Which clause should you use in your SQL statement?

    1. FOR XML AUTO

    2. FOR XML RAW

    3. FOR XML EXPLICIT

    4. FOR XML AUTO, XMLDATA

  11. Your application contains the following code:

    private void btnReadXML_Click(
      object sender, System.EventArgs e)
    {
      // Create a command to retrieve XML
      SqlCommand sc =
        SqlConnection1.CreateCommand();
      sc.CommandType = SqlCommandType.Text;
      sc.CommandText =
       "SELECT Customers.CustomerID, " +
       "Customers.CompanyName," +
       "Orders.OrderID, Orders.OrderDate " +
       "FROM Customers INNER JOIN Orders " +
       "ON Customers.CustomerID = " +
       "Orders.CustomerID "
       + "WHERE Country = 'Brazil' AND " +
       "OrderDate BETWEEN '1997-03-15' " +
       "AND '1997-04-15' " +
       "FOR XML AUTO, ELEMENTS";
      // Read the XML into an XmlReader
      XmlReader xr = sc.ExecuteXmlReader();
      XmlDocument xd = new XmlDocument();
      xd.Load(xr);
    }

    When you run this code, you receive an error on the line of code that attempts to load the XmlDocument. What can you do to fix the problem?

    1. Use FOR XML RAW instead of FOR XML AUTO in the SQL statement.

    2. Replace the XmlDocument object with an XmlDataDocument object.

    3. Replace the SqlCommand object with a SqlXmlCommand object.

    4. Replace the XmlReader object with an XmlTextReader object.

  12. Your application contains the following code, which uses the SQLXML managed classes to apply a DiffGram to a SQL Server database:

    private void btnUpdate_Click(
      object sender, System.EventArgs e)
    {
      // Connect to the SQL Server database
      SqlXmlCommand sxc =
       new SqlXmlCommand(
       "Provider=SQLOLEDB;" +
       "Server=(local);database=Northwind;" +
       "Integrated Security=SSPI");
    
      // Set up the DiffGram
      sxc.CommandType =
        SqlXmlCommandType.DiffGram;
      FileStream fs =
       new FileStream(@"..\..\diffgram.xml",
        FileMode.Open);
      sxc.CommandStream = fs;
      // And execute it
      sxc.ExecuteNonQuery();
      MessageBox.Show(
        "Database was updated!");
    } 

    When you run the code, it does not update the database. The DiffGram is properly formatted. What should you do to correct this problem?

    1. Use a SqlCommand object in place of the SqlXmlCommand object.

    2. Supply an appropriate schema mapping file for the DiffGram.

    3. Store the text of the DiffGram in the CommandText property of the SqlXmlCommand object.

    4. Use a SqlConnection object to make the initial connection to the database.

  13. Which of these operations can be carried out in a SQL Server database by sending a properly-formatted DiffGram to the database? (Select two.)

    1. Adding a row to a table

    2. Adding a primary key to a table

    3. Deleting a row from a table

    4. Changing the data type of a column

  14. You are developing code that uses the XPathNavigator object to navigate among the nodes in the DOM representation of an XML document. The current node of the XPathNavigator is an element in the XML document that does not have any attributes or any children. You call the MoveToFirstChild() method of the XPathNavigator object. What is the result?

    1. The current node remains unchanged and there is no error.

    2. The current node remains unchanged and a runtime error is thrown.

    3. The next sibling of the current node becomes the current node and there is no error.

    4. The next sibling of the current node becomes the current node and a runtime error is thrown.

  15. Which of these operations requires you to have an XML schema file?

    1. Updating a SQL Server database with a DiffGram through the SQLXML Managed classes

    2. Validating an XML file with the XmlValidatingReader class

    3. Performing an XPath query with the XPathNavigator class

    4. Reading an XML file with the XmlTextReader class

Answers to Review Questions

  1. XML elements are represented as nodes within the DOM. XML attributes are represented as properties of their parent nodes.

  2. The XmlTextReader object provides forward-only, read-only access to XML data. For random access or for read-write access you should use the XmlDocument class or one of its derived classes.

  3. You can synchronize an XmlDataDocument object and a DataSet object by creating a DataSet object from an XmlDataDocument object, by creating an XmlDataDocument object from a DataSet object, or by creating both a DataSet object and an XmlDataDocument object from a schema.

  4. XPath expressions containing an explicit path, such as /Customers/Customer/Order/OrderID, are faster to evaluate than documentwide wildcard expressions such as //OrderID.

  5. /Customers/Customer/Order[1] selects the first order for each customer, whereas (/Customers/Customer/Order)[1] selects the first order in the entire document.

  6. You can instantiate an XPathNavigator object by calling the CreateNavigator() method of the XmlDocument, XmlDataDocument, or XPathDocument classes.

  7. You can use an XmlValidatingReader object to validate an XML file for conformance with an embedded schema, an XSD file, a DTD file, or an XDR file.

  8. The three main variants of FOR XML are FOR XML RAW, FOR XML AUTO, and FOR XML EXPLICIT.

  9. To include schema information with a FOR XML query, specify the XMLDATA option.

  10. DiffGrams can represent insertions, deletions, and modifications of the data in a DataSet object or SQL Server database.

Answers to Exam Questions

  1. D. When you read XML data with the help of XmlReader or its derived classes, nodes are not included for XML attributes, but only for XML elements and the text that they contain. XML element nodes do not have a value. The only text that will be printed out is the value of the text nodes within the OrderDate elements. For more information, see the section "Accessing an XML File" in this chapter.

  2. B. The ReadXmlSchema() method maps nested elements in the XML file to related DataTable objects in the DataSet object. At the leaf level of the DOM tree, both elements and attributes are mapped to DataColumn objects. For more information, see the section "Synchronizing DataSet Objects with XML" in this chapter.

  3. D. Looping through all the nodes in an XmlDocument object is comparatively slow. If you start with the full XML document or by calling the ReadXml() method of the DataSet object, the DataSet object will contain all 50 elements. Using a schema file enables you to limit the DataSet object to holding only the desired data. For more information, see the section "Synchronizing DataSet Objects with XML" in this chapter.

  4. C. The DataSet and the XmlDataDocument objects represent two different views of the same data structure. The last change made to either view is the change that is written back to the database. For more information, see the section "Synchronizing DataSet Objects with XML" in this chapter.

  5. C. /Customers/Customer/Orders/Order/@OrderID[1] selects the first OrderID for each order. (/Customers/Customer/Orders/Order)[1]/ @OrderID selects the OrderID for the first order in the entire file. (/Customers/Customer/Orders/Order/@OrderID)[1] selects the first OrderID in the entire file. The remaining choice is the correct one. For more information, see the section "Understanding XPath" in this chapter.

  6. A. The filtering expression needs to start with the ./ operator to indicate that it is filtering nodes under the current node at that point in the expression. For more information, see the section "Understanding XPath" in this chapter.

  7. D. The XPathDocument class is optimized for read-only XPath queries. For more information, see the section "Understanding XPath" in this chapter.

  8. A. The XPathNavigator object provides random access movement within the DOM. The XmlReader and XmlTextReader objects provide forward-only movement. The XPathExpression object is useful for retrieving a set of nodes, but not for navigating between nodes. For more information, see the section "Using the XPathNavigator Class" in this chapter.

  9. B. An inline schema cannot contain validation information for the root node of the document, so XML documents with inline schemas will always have at least one validation error. For more information, see the section "Using an XSD Schema" in this chapter.

  10. C. The raw and auto modes of the FOR XML statement always map columns to attributes, if the ELEMENTS option is not added in the FOR XML clause. Only explicit mode can map a column to an element. For more information, see the section "Understanding the FOR XML Clause" in this chapter.

  11. C. The SqlCommand.ExecuteXmlReader() method returns an XML fragment rather than an XML document. To load a complete and valid XML document, you need to use the SqlXmlCommand object (from the SQLXML Managed Classes) instead. For more information, see the section "Updating SQL Data by Using XML" in this chapter.

  12. B. When executing a DiffGram via the SQLXML managed classes, you must supply a mapping schema file. Otherwise, the code doesn't know which elements in the DiffGram map to which columns in the database. For more information, see the section "Using DiffGrams" in this chapter.

  13. A, C. DiffGrams are useful for performing data manipulation operations, but not for data definition operations. For more information, see the section "Using DiffGrams" in this chapter.

  14. A. The MoveTo methods of the XPathNavigator object always execute without error. If the requested move cannot be performed, the current node remains unchanged and the method returns false. For more information, see the section "Using the XPathNavigator Class" in this chapter.

  15. A. You cannot perform a DiffGram update without a schema file that specifies the mapping between XML elements and database columns. Validation can be performed with a DTD or XDR file instead of a schema. XPath queries and reading XML files do not require a schema. For more information, see the section "Using DiffGrams" in this chapter.

Suggested Readings and Resources

  1. Visual Studio .NET Combined Help Collection

    • Employing XML in the .NET Framework

    • XML and the DataSet

  2. Microsoft SQL Server Books Online

    • Retrieving XML Documents Using FOR XML

    • SELECT Statement

  3. .NET Framework QuickStart Tutorials, Common Tasks QuickStart, XML section.

  4. Mike Gunderloy. ADO and ADO.NET Programming. Sybex, 2002.

  5. John E. Simpson. XPath and XPointer. O'Reilly, 2002.

  6. John Griffin. XML and SQL Server. New Riders, 2001.

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Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020