Home > Articles > Web Services > XML

  • Print
  • + Share This
This chapter is from the book

Relational Databases

Relational databases are another common source of data for XML documents. Some databases such as FileMaker Pro have built-in support for outputting tables as XML documents. Others do not. However, even if your database can export tables as XML documents, its XML format may not be the XML format you want. Fortunately, as long as there's a JDBC driver for your database of choice, it's not hard to extract the information from it and write that information into an XML document in the desired form.

For this example, I'll use the same budget data previously read out of a CSV file in a single relational table that reflects the original flat structure of the files distributed by the Office of Management and Budget. Doubtless they have the data in their own relational databases, probably divided up into multiple tables; but they don't publish it that way. They do state, “If you plan to use these data in a relational database, you should designate the following fields as 'primary' to uniquely identify each row of data: agency code, bureau code, account code, subfunction code, BEA category, Grant/Nongrant, and On- Off-budget field.” The SQL CREATE TABLE statement that initializes this table is as follows:

CREATE TABLE BudgetAuthorizationTable ( 
  AgencyCode             CHAR(3),
  AgencyName             VARCHAR(89),
  BureauCode             CHAR(2),
  BureauName             VARCHAR(89),
  AccountCode            VARCHAR(6),
  AccountName            VARCHAR(160),
  TreasuryAgencyCode     CHAR(2),
  SubfunctionCode        CHAR(3),
  SubfunctionTitle       VARCHAR(72),
  BEACategory            VARCHAR(13),
  On-Off-BudgetIndicator VARCHAR(10),
  FY1976                 INTEGER,
  TransitionQuarter      INTEGER,
  FY1977                 INTEGER,
  FY1978                 INTEGER,
  FY1979                 INTEGER,
  FY1980                 INTEGER,
  FY1981                 INTEGER,
  FY1982                 INTEGER,
  FY1983                 INTEGER,
  FY1984                 INTEGER,
  FY1985                 INTEGER,
  FY1986                 INTEGER,
  FY1987                 INTEGER,
  FY1988                 INTEGER,
  FY1989                 INTEGER,
  FY1990                 INTEGER,
  FY1991                 INTEGER,
  FY1992                 INTEGER,
  FY1993                 INTEGER,
  FY1994                 INTEGER,
  FY1995                 INTEGER,
  FY1996                 INTEGER,
  FY1997                 INTEGER,
  FY1998                 INTEGER,
  FY1999                 INTEGER,
  FY2000                 INTEGER,
  FY2001                 INTEGER,
  FY2002                 INTEGER,
  FY2003                 INTEGER,
  FY2004                 INTEGER,
  FY2005                 INTEGER,
  FY2006                 INTEGER,
  PRIMARY KEY (AgencyCode, BureauCode, AccountCode,
               SubfunctionCode, BEACategory, On-Off-BudgetIndicator)

The specific database I chose for this example is Microsoft Excel, mostly because it could very easily read the CSV files with which I started. Excel isn't the best example of a relational database. In fact, it isn't a relational database at all. But Excel does allow you to define a range of cells as a table, and then associate that table with an ODBC data source. This data source can then be read with SQL using JDBC through the JdbcOdbcDriver, which is all I really want to show here. Aside from the choice of JDBC driver, all statements will be completely database independent. The name of the ODBC data source is budauth. The name of the table in that source is BudgetAuthorizationTable.

Extracting the necessary data from the database is just a matter of SQL, which as a Java developer, you access via JDBC. To some extent you can let the database do the hard work for you by executing the right sequence of SQL commands. In this case, this simply consists of a long sequence of nested SELECT statements. SQL 's DISTINCT operator will be particularly helpful. The contortions of the Muenchian method in Example 4.12 were a roundabout way of providing a distinct operation in XSLT. Example 4.14 demonstrates.

Example 4.14 A Program That Connects to a Relational Database Using JDBC and Converts the Table to Hierarchical XML

import java.sql.*;
import java.io.*;
public class SQLToXML {

  public static void main(String[] args ) {

    // Load the ODBC driver
    try {
      Class.forName( "sun.jdbc.odbc.JdbcOdbcDriver" );
    catch (ClassNotFoundException e) {
      System.err.println("Could not load the JDBC-ODBC Bridge");

    try {
      Writer out = new OutputStreamWriter(System.out, "UTF8");
      out.write("<?xml version=\"1.0\"?>\r\n");
    catch (IOException e) {


  private static void writeAgencies(Writer out)
   throws IOException {

    Connection conn = null;
    Statement stmnt = null;
    try {
      conn = DriverManager.getConnection(
       "jdbc:odbc:budauth", "", "");
      stmnt = conn.createStatement();
      String query = "SELECT DISTINCT AgencyName, AgencyCode"
       + " FROM BudgetAuthorizationTable;";
      ResultSet agencies = stmnt.executeQuery( query );
      while( agencies.next() ) {

        String agencyName = agencies.getString("AgencyName");
        agencyName = escapeText(agencyName);
        String agencyCode = agencies.getString("AgencyCode");
        out.write("  <Agency>\r\n");
        out.write("    <Name>" + agencyName + "</Name>\r\n");
        out.write("    <Code>" + agencyCode + "</Code>\r\n");
        writeBureaus(out, conn, agencyCode);
        out.write("  </Agency>\r\n");

    catch (SQLException e) {
    finally {
      try {
      catch(SQLException e) {


  private static void writeBureaus(Writer out, Connection conn,
   String agencyCode) throws IOException, SQLException {

    String query
     = "SELECT DISTINCT BureauName, BureauCode "
     + "FROM BudgetAuthorizationTable WHERE AgencyCode='"
     + agencyCode + "';";
    Statement stmnt = conn.createStatement();
    ResultSet bureaus = stmnt.executeQuery(query);

    while( bureaus.next() ) {
      String bureauName = bureaus.getString("BureauName");
      bureauName = escapeText(bureauName);
      String bureauCode = bureaus.getString("BureauCode");
      out.write("    <Bureau>\r\n");
      out.write("      <Name>" + bureauName + "</Name>\r\n");
      out.write("      <Code>" + bureauCode + "</Code>\r\n");
      writeAccounts(out, conn, agencyCode, bureauCode);
      out.write("    </Bureau>\r\n");


  private static void writeAccounts(Writer out, Connection conn,
   String agencyCode, String bureauCode)
   throws IOException, SQLException {

    String query = "SELECT DISTINCT AccountName, AccountCode "
     + "FROM BudgetAuthorizationTable WHERE AgencyCode='"
     + agencyCode + "' AND BureauCode='" + bureauCode + "';";
    Statement stmnt = conn.createStatement();
    ResultSet accounts = stmnt.executeQuery(query);

    while( accounts.next() ) {
      String accountName = accounts.getString("AccountName");
      accountName = escapeText(accountName);
      String accountCode = accounts.getString("AccountCode");
      out.write("      <Account>\r\n");
      out.write("        <Name>" + accountName + "</Name>\r\n");
      out.write("        <Code>" + accountCode + "</Code>\r\n");
       out, conn, agencyCode, bureauCode, accountCode
      out.write("      </Account>\r\n");


  private static void writeSubfunctions(Writer out,
   Connection conn, String agencyCode, String bureauCode,
   String accountCode) throws IOException, SQLException {
    String query = "SELECT * FROM BudgetAuthorizationTable"
     + " WHERE AgencyCode='" + agencyCode + "' AND BureauCode='"
     + bureauCode + "' AND AccountCode='" + accountCode + "';";
    Statement stmnt = conn.createStatement();
    ResultSet subfunctions = stmnt.executeQuery(query);

    while( subfunctions.next() ) {
      String subfunctionTitle
       = subfunctions.getString("SubfunctionTitle");
      subfunctionTitle = escapeText(subfunctionTitle);
      String subfunctionCode
       = subfunctions.getString("SubfunctionCode");
      out.write("        <Subfunction>\r\n");
      out.write("          <Name>");
      out.write("          <Code>");
      out.write("          <Amount year='TransitionQuarter'>");
       + "</Amount>\r\n");
      for (int year = 1976; year <= 2006; year++) {
        String name = "FY" + year;
        long amt = subfunctions.getInt(name) * 1000L;
        out.write("          <Amount year='" + year + "'>");
        out.write(amt + "</Amount>\r\n");
      out.write("        </Subfunction>\r\n");


  public static String escapeText(String s) {

    if (s.indexOf('&') != -1 || s.indexOf('<') != -1
     || s.indexOf('>') != -1 || s.indexOf('"') != -1
     || s.indexOf('\'') != -1 ) {
      StringBuffer result = new StringBuffer(s.length() + 6);
      for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        if (c == '&') result.append("&amp;");
        else if (c == '<') result.append("&lt;");
        else if (c == '"') result.append("&quot;");
        else if (c == '\'') result.append("&apos;");
        else if (c == '>') result.append("&gt;");
        else result.append(c);
      return result.toString();
    else {
      return s;



The basic approach here should be quite familiar by now. Tags are stored in string literals. These tags are written onto a Writer along with element content and attribute values that have been read from the input. The difference in this case is that because the input comes from a relational database, the program can use SQL to get the input it wants when it wants it. The Java program does not need to put itself out to accommodate the order of the input data. In essence this program is nothing more than four nested loops. The outermost loop iterates over the different agencies. This contains a loop that iterates over the bureaus within that agency. This contains a loop that iterates over the accounts within that bureau. This contains the innermost loop, which iterates over the subfunctions within the account. Compare this to the contortions the other programs had to perform. Only the XQuery solution was as straightforward as this—not surprising, because it also allows the client to specify which data it wants to receive.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


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.


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.


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.


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


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


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.


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.


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