app.js

Ti.App.Properties.setList('DB_queue', []);
Ti.App.Properties.setBool('DB_locked', false);
Ti.App.Properties.setBool('DB_queue_running', false);

Ti.include('db.js', 'examples.js');

db.js

var DB = Ti.Database.open('');

var Database = D = {
    'queue': Ti.App.Properties.getList('DB_queue', []),
    'locked': Ti.App.Properties.getBool('DB_locked', false),
    'running': Ti.App.Properties.getBool('DB_queue_running', false),
    'isValidRow': false,
    'rows': [],
    'fields': {
        '*': [] // instead of ['all', 'fields', 'must', 'be', 'used', 'with', '*'] store them here and use D.fields['*'] for a shortcut
    },
    lockDB: function() {
        this.locked = true;
        Ti.App.Properties.setBool('DB_locked', true);
    },
    unlockDB: function() {
        this.locked = false;
        Ti.App.Properties.setBool('DB_locked', false);
    },
    addQueueItem: function(params) {
        this.queue.push(params);
        Ti.App.Properties.setList('DB_queue', this.queue);
        this.runQueue();
    },
    runQueueItem: function(params) {
        Ti.API.info('beforeRun -> DB_locked: '+this.locked);
        this.lockDB();
        Ti.API.info('onRun -> DB_locked: '+this.locked);
        DB = Ti.Database.open('starleads_01');
        this.isValidRow = false;
        switch(params.type) {
            case 'create':
                DB.execute(params.sql);
            break;
            case 'select':
                if(params.selectWhere) {
                    var rows = DB.execute(params.sql, params.args);
                } else {
                    var rows = DB.execute(params.sql);
                }
                var results = [];
                while(rows.isValidRow()) {
                    this.isValidRow = true;
                    var row = {};
                    for(var i=0,l=params.fields.length;i<l;i++) {
                        row[params.fields[i]] = rows.field(i);
                     }
                     results.push(row);
                    rows.next();
                }
                this.rows = results;
                rows.close();
            break;
            case 'insert':
                DB.execute(params.sql, params.args);
            break;
            case 'update':
                DB.execute(params.sql, params.args);
            break;
            case 'delete':
                DB.execute(params.sql, params.args);
            break;
        }
        DB.close();
        this.unlockDB();
        Ti.API.info('afterRun - >DB_locked: '+this.locked);
    },
    runQueue: function() {
        this.running = true;
        Ti.App.Properties.setBool('DB_queue_running', true);
        if(this.locked) {
            Ti.API.info('locked -> runQueue');
            this.runQueue();
        } else {
            Ti.API.info('unlocked -> que: '+ this.queue.length);
            if(this.queue.length > 0) {
                Ti.API.info('runQueueItem');
                var queueItem = this.queue.shift();
                this.runQueueItem(queueItem);
                this.runQueue();
            } else {
                this.running = false;
                Ti.App.Properties.setBool('DB_queue_running', false);
            }
        }
    },
    exec: function(params) {
        if(this.locked) {
            this.addQueueItem(params);
        } else {
            this.runQueueItem(params);
        }
    }
};

examples.js

// CREATE
D.exec({
    type: 'create',
    sql: 'CREATE TABLE SYNTAX'
});

// INSERT
D.exec({
    type: 'insert',
    sql: 'INSERT INTO SYNTAX',
    args: ['field1', 'field2']
});

// SELECT w/out WHERE
D.exec({
    type: 'select',
    sql: 'SELECT * FROM SYNTAX',
    fields: ['all', 'fields', 'must', 'be', 'used', 'with', '*']
});
alert(D.rows);

D.exec({
    type: 'select',
    sql: 'SELECT field1, field2 FROM SYNTAX',
    fields: ['field1', 'field2']
});
alert(D.rows);

// SELECT w/ WHERE
D.exec({
    type: 'select',
    selectWhere: true,
    sql: 'SELECT * FROM table WHERE ARG = ? SYNTAX',
    fields: ['all', 'fields', 'must', 'be', 'used', 'with', '*'],
    args: [ARG]
});
alert(D.rows);

// UPDATE
D.exec({
    type: 'update',
    sql: 'UPDATE table SET field1 = ?, field2 = ? WHERE ARG = ?',
    args: ['field1', 'field2', 'ARG']
});

// DELETE
D.exec({
    type: 'delete',
    sql: 'DELETE FROM table WHERE ARG = ?',
    args: [ARG]
});

// ROW EXISTS
D.exec({
    type: 'select',
    selectWhere: true,
    sql: 'SELECT * FROM table WHERE ARG = ?',
    fields: ['all', 'fields', 'must', 'be', 'used', 'with', '*']
    args: [ARG]
});
alert(D.isValidRow);