title: how to use window.openDatabase to access the old db in phonegap?
body: <p>I read the storage tutorial in PhoneGap dev page. 
  In the example, it used the window.openDatabase twice. But the document says openDatabase return a new db object, I guess the goal of the example is to generate a new DB and then access it to get the data back. But then why did it create a new db object twice??</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
    &lt;head&gt;
      &lt;title&gt;Storage Example&lt;/title&gt;
  
      &lt;script type="text/javascript" charset="utf-8" src="cordova-1.8.1.js"&gt;&lt;/script&gt;
      &lt;script type="text/javascript" charset="utf-8"&gt;
  
      // Wait for Cordova to load
      //
      document.addEventListener("deviceready", onDeviceReady, false);
  
      // Populate the database 
      //
      function populateDB(tx) {
          tx.executeSql('DROP TABLE IF EXISTS DEMO');
          tx.executeSql('CREATE TABLE IF NOT EXISTS DEMO (id unique, data)');
          tx.executeSql('INSERT INTO DEMO (id, data) VALUES (1, "First row")');
          tx.executeSql('INSERT INTO DEMO (id, data) VALUES (2, "Second row")');
      }
  
      // Query the database
      //
      function queryDB(tx) {
          tx.executeSql('SELECT * FROM DEMO', [], querySuccess, errorCB);
      }
  
      // Query the success callback
      //
      function querySuccess(tx, results) {
    console.log("Returned rows = " + results.rows.length);
    // this will be true since it was a select statement and so rowsAffected was 0
    if (!results.rowsAffected) {
      console.log('No rows affected!');
      return false;
    }
    // for an insert statement, this property will return the ID of the last inserted row
    console.log("Last inserted row ID = " + results.insertId);
      }
  
      // Transaction error callback
      //
      function errorCB(err) {
          console.log("Error processing SQL: "+err.code);
      }
  
      // Transaction success callback
      //
      function successCB() {
          var db = window.openDatabase("Database", "1.0", "Cordova Demo", 200000); //Why create a new DB again??
          db.transaction(queryDB, errorCB);
      }
  
      // Cordova is ready
      //
      function onDeviceReady() {
          var db = window.openDatabase("Database", "1.0", "Cordova Demo", 200000);
          db.transaction(populateDB, errorCB, successCB);     //upon the success of create a database, jump to successCB
      }
  
      &lt;/script&gt;
    &lt;/head&gt;
    &lt;body&gt;
      &lt;h1&gt;Example&lt;/h1&gt;
      &lt;p&gt;Database&lt;/p&gt;
    &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>