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474

Chapter 18 JDBC and Database Connection Pooling

4.

printTableData

Given a 

DBResults

 object from a previous query, this method 

prints it on the standard output. This is the underlying method 

used by 

printTable

, but it is also useful for debugging arbi 

trary database results.

Listing 18.6 gives the main code, and Listing 18.7 presents the auxiliary

DBResults

 class that stores the accumulated results and returns them as

arrays of strings (

getRow

) or wrapped up inside an HTML table (

toHTML 

Table

). For example, the following two statements perform a database query,

retrieve the results, and format them inside an HTML table that uses the col 

umn names as headings with a cyan background color.

DBResults results =

DatabaseUtilities.getQueryResults(driver, url,

                                    username, password,

                                    query, true);

out.println(results.toHTMLTable("CYAN"));

Since an HTML table can do double duty as an Excel spreadsheet (see

Section 11.2), the 

toHTMLTable

 method provides an extremely simple

method for building tables or spreadsheets from database results.

 Remember that the source code for 

DatabaseUtilities

 and 

DBResults

,

like all the source code in the book, can be downloaded from 

www.core 

servlets.com

 and used or adapted without restriction. 

Listing 18.6  DatabaseUtilities.java 

package coreservlets;

import java.sql.*;

public class DatabaseUtilities {

  /** Connect to database, execute specified query,

   *  and accumulate results into DBRresults object.

   *  If the database connection is left open (use the

   *  close argument to specify), you can retrieve the

   *  connection with DBResults.getConnection.

   */

  public static DBResults getQueryResults(String driver,

                                          String url,

                                          String username,

                                          String password,

                                          String query,

                                          boolean close) {

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