proposed simpledb lib change.js

Sdb.prototype.getQueryString = function(query) {
    if (!query.domain) throw new Error('no domain specified');
    
    if (!query.fields || !query.fields.length) query.fields = '*';
    
    var str = query.fields.join() + ' from ' + query.domain;
    
    if (query.selectors && query.selectors.length) 
        str+= ' where ' + query.selectors.join(' intersection ');
        
    if (query.order) str+= ' order by ' + query.order;
    
    if (query.limit) str+= ' limit ' + query.limit;
    
    return str;
}

Sdb.prototype.select = function(query, token) { 
	if (!query) throw new Error('no query specified');
	
	// can pass a query object with <fields [], domain str, selectors [], limit int, order str>
	if (typeof(query) != 'string') query = this.getQueryString(query);
	
	this.params.SelectExpression = 'select ' + query;
	
	if (token) this.params.NextToken = token;
	
	return this.request('Select');
};