Question

try {
    Statement stmt = con.createStatement();
    stmt.executeUpdate("INSERT into emailacc(fname,lname,uname,mail,passwd,passwd2,date,month,year) values('"+fname+","+lname+","+uname+","+mail+","+passwd+","+passwd2+","+date+","+selectMonth+","+year+"')");
    out.println("<h3><font color='green'>Information Added Successfully.</font><br> You Are a registered User now.</h3><br>");
    con.close();
} catch(Exception e) {
    out.println("Exception caught : "+e);   
}

Why is it happening?
Last time I did the same but it didn’t happen, whats wrong with it?

Answer 1

Is because you are omitting single quotes, for avoid this mistakes my recommendation is to use PreraredStatement, also in order to proper close connection it mus be in a finally block , you code must look at this:

    try {
        PreparedStatement stmt = con.prepareStatement("INSERT into emailacc(fname,lname,uname,mail,passwd,passwd2,date,month,year) values(?,?,?,?,?,?,?,?,?)");
        stmt.setString(1,fname);
        stmt.setString(2,lname);
        stmt.setString(3,uname);
        stmt.setString(4,mail);
        stmt.setString(5,passwd);
        stmt.setString(6,passwd2);
        stmt.setDate(7,date); //you need convert your date to java.sql.Date if 'date' field of database is of type date. If not setString is fine
        stmt.setInt(8,selectMonth);
        stmt.setInt(9,year);
        stmt.executeUpdate();
        out.println("<h3><font color='green'>Information Added Successfully.</font><br> You Are a registered User now.</h3><br>");
    } catch (Exception e) {
        con.rollback();
        out.println("Exception caught : " + e);
    } finally {
        if (con != null) {
            try {
                con.close();
            } catch(SQLException ex){
                //DO NOTHING
            }
        }
    }

You can learn more of PreparedStatemt in:

http://download.oracle.com/javase/tutorial/jdbc/basics/prepared.html

A final note: PreparedStament are more efficent thant Statement and avoid the SQL Injection hack so PrepararedStatement is more secure. Try use always a PreparedStatement