How to use mysql-connector-driver with jsp

Question

I need to create a login with JSP and so, I need to use mysql-connector-java.

I insert the file jar: mysql-connector-java-5.1.38-bin.jar into WEB-INF/lib

and I use this code into the jsp file:

<%@ 
        page import="java.sql.*"
    %>

<%
    String DRIVER = "com.mysql.jdbc.Driver";
    String URL_mioDB = "jdbc:mysql://localhost:3306/ditta";

    try
    {
       Class.forName(DRIVER);
    } 
    catch (ClassNotFoundException e) 
    {
       System.err.println("Driver not found" + e);
    } 

    Connection connessione = null;
    try
    {
       // apro la connesione verso il database.
       connessione = DriverManager.getConnection(URL_mioDB,"root","");
    } 
    catch (Exception e)
    {
       System.err.println("Error during connection with db : " + e);
    } 

    String mail="",pass="",send="",query="";

    try
    {
        mail=request.getParameter("email");
        pass=request.getParameter("password");
        send=request.getParameter("send");

        out.println("<FORM name='F1' method='post' action='login.jsp'>");
            out.println("Email: <INPUT type='text' name='email' value='' placeholder='mariorossi@gmail.com'><BR><BR>");
            out.println("Password: <INPUT type='password' name='password' value=''><BR><BR>");
            out.println("<INPUT type='submit' name='send' value='Invia'>&nbsp;&nbsp;&nbsp;&nbsp;<INPUT type='reset' name='reset' value='Reset'>");
        out.println("</FORM>");
    }
    catch (Exception e)
    {
       System.err.println(e);  
    } 

    if(send!=null && mail!="" && pass!="")
    {
        query="SELECT * FROM dipendenti WHERE email="+ mail + " AND password=" + pass + "";

        Statement statement = connessione.createStatement();
        ResultSet resultSet = statement.executeQuery(query);
        ResultSetMetaData rsmd = resultSet.getMetaData();

        for(int i=0;i<=rsmd.getColumnCount();i++)
        {
            out.println(resultSet.getString(i));
            }
    }

%>

after that, When I click on the send button the page give me this error:

errors image

Answer 1

Guessing a bit here...

I guess it might be about how you pass values of the parameters into the query. So if mail is "a@a.com" and password is "a", then your query ends up being:

SELECT * FROM dipendenti WHERE email=a@a.com AND password=a

This is not a proper SQL. You are missing the quotes/apostrophes. I'd try reaching a query like this:

SELECT * FROM dipendenti WHERE email='a@a.com' AND password='a'

which requires a simple change on how you define

query=...

---

At the same time, I know this is not what you are asking here, but I strongly suggest you should read about SQL Injection on Wikipedia . What you are doing here is not a proper way of accepting user input into your back-end program and eventually into the database.

For this very specific use-case JDBC (and databases) has a notion of Prepared Statements: http://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html

So you would start with something similar to:

    // not tested
    query="SELECT * FROM dipendenti WHERE email=? AND password=?";
    PreparedStatement statement = connessione.prepareStatement(query);

    statement.setString(1, mail);
    statement.setString(2, pass);

    ResultSet resultSet = statement.executeQuery();