为什么我无法查询我的sqlite数据库？

Question

我正在建立一个带有phonegap和类固醇js的应用程序。为了将数据保存到sqlite数据库，您需要使用cordova存储API。这就是我正在做的事情。我在成功时收到警报消息，但查询我的数据库并不起作用。
Here's info on the storage api

我的代码：

 var result = 'string for now';
 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, "'+ result +'")');
 tx.executeSql('INSERT INTO DEMO (id, data) VALUES (2, "Second row")');
}

function errorCB(err) {
alert("Error processing SQL: "+err.code);
}

function successCB() {
alert("success!");
db.transaction(queryDB, errorCB);
}

function queryDB(tx) {
tx.executeSql('SELECT * FROM DEMO', [], querySuccess, errorCB);
}

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);
}


var db = window.openDatabase("Database", "1.0", "Cordova Demo", 200000);
db.transaction(populateDB, errorCB, successCB);