function MySQLDatabase(){

	var result;
	var outputText;
	var row;
	var error;

	var pointer;

	this.query = function(sql){

		var oXML;

		this.pointer = 0;

		if(window.XMLHttpRequest){
			oXML = new XMLHttpRequest();
		}else{

			try {
				oXML = new ActiveXObject("Microsoft.XMLHTTP");
			}catch (e) {
				alert("El navegador utilizado no está soportado");
				return(false);
			}
		}

		var cadena_query = "includes/xml_query.php?query=" + encodeURI(sql) + "&rand_" + aleatorio(0,99999);
		oXML.open("post",cadena_query ,false);
		oXML.send(null);

		if(oXML.status != "200"){
			alert("Error de conexion: " + oXML.status + " - " + statusText);
			return false;
		}

		var resultado = oXML.responseXML;

		if(resultado.getElementsByTagName('error').length != 0){
			this.error = true;
		}

		this.result = oXML.responseXML;
		this.outputText = oXML.responseText;
	}

	this.showError = function(){
		if(this.error){
			alert(this.result.getElementsByTagName('error')[0].firstChild.data + "\nQuery: " + query);
		}else{
			alert("No errors!");
		}
	}

	this.showOutput = function(){
		alert(this.outputText);
	}

	this.nextRow = function(){
		if(this.pointer == this.result.getElementsByTagName('fila').length){
			return(false);
		}else{
			this.row = this.result.getElementsByTagName('fila')[this.pointer];
			this.pointer++;
			return(true);
		}
	}

	this.prevRow = function(){
		if(this.pointer == 0){
			return(false);
		}else{
			this.pointer--;
			this.row = this.result.getElementsByTagName('fila')[this.pointer];
			return(true);
		}
	}

	this.getField = function(field){
		return(this.row.getElementsByTagName(field)[0].firstChild.data);
	}

	this.getNumRows = function(){
		return(this.result.getElementsByTagName('fila').length);
	}

	this.getCurrentPointer = function(){
		return(this.pointer);
	}

	this.setPointer = function(num){
		this.pointer = num;
	}

	this.resetPointer = function(){
		this.pointer = 0;
	}

	this.setEndPointer = function(){
		this.pointer = this.result.getElementsByTagName('fila').length-1;
	}
}