why, oh why?

could anyone, please, explain to me why the code below doesn't work?

<%@ page import="java.sql.*, java.util.*, java.util.Date, java.text.*, java.lang.*" %>

<%

boolean erro_f=false;

boolean erro_q=false;

boolean achou=true;

String codigo_estabelecimento="";

int ncodigo_estabelecimento=0;

String senha_estabelecimento="";

String codigo_cliente="";

int ncodigo_cliente=0;

String senha_cliente="";

String pedido="";

int npedido=0;

int parcelas=1;

String dia="";

String mes="";

String ano="";

String data="";

String[] data_parcela=new String[5];

double[] parcela=new double[5];

double valor;

String clear=(String) session.getAttribute("clear");

String submited=request.getParameter("submited");

codigo_estabelecimento=(String) session.getValue("MM_Username");

Class.forName("org.gjt.mm.mysql.Driver");

String url="jdbc:mysql://sql.linkway.com.br/cons_redecon";

Connection con=DriverManager.getConnection(url, "desenvest4","ecii9uie");

Statement st=con.createStatement();

ResultSet res=null;

//senha_estabelecimento=request.getParameter("senha_estabelecimento");

codigo_cliente=request.getParameter("codigo_cliente");

senha_cliente=request.getParameter("senha_cliente");

pedido=request.getParameter("pedido");

data=request.getParameter("data");

parcelas=Integer.parseInt(request.getParameter("parcelas"));

for (int i=0;i<5;i++) {

try {

parcela=Double.parseDouble(request.getParameter("valor0"+(i+1)).replace(',','.'));

} catch (Exception e) {

parcela=0;

}

res.executeQuery("select DATE_ADD('"+data+"', INTERVAL "+(i+1)+" MONTH) as parcela");//<-the error occurs here

achou=res.next();

data_parcela=res.getString("parcela");

}

... and it goes on... but that's trully enough... please, help me..

[2029 byte] By [jdqo] at [2007-9-26 2:40:55]
# 1
what kind of error are you getting?
wmacey at 2007-6-29 10:15:44 > top of Java-index,Enterprise & Remote Computing,Web Tier APIs...
# 2
Your trying to execute the query with the resultset but what you want to do is use the statement.
bobd3 at 2007-6-29 10:15:44 > top of Java-index,Enterprise & Remote Computing,Web Tier APIs...