Java Servlet & MySQL

Question

What's wrong with this code? It gives me "brand" = null.

public String getBrand(@WebParam(name = "regNr") String regNr) throws SQLException {

    String brand=null;
    Connection con;
    Statement st;
    ResultSet rs;

    String url = "jdbc:mysql://db4free.net:3606/cars";
    String user = "cars";
    String password = "";

    try {
        con = (Connection) DriverManager.getConnection(url, user, password);
        st = (Statement) con.createStatement();
        rs = st.executeQuery("SELECT * FROM Cars WHERE nr= '" + regNr + "'");

        if (rs.next()) {
            brand=rs.getString("brand");
        }


    } catch (SQLException ex) {

    }
    return brand;
}

I want to display the value of brand from database. Is it a problem with connection?

Asaph · Accepted Answer · 2013-11-30 22:43:44Z

1

Either the query isn't returning any rows or a SQLException is being thrown. Add something to your catch block to discover what the exception is.

BTW: You should be calling close() on your ResultSet, Statement and Connection instances. I suggest putting those calls within a finally block. Additionally, your code is vulnerable to an attack called SQL injection. Use a PreparedStatement with parameters to repair this problem.

answered Nov 30, 2013 at 22:43

Asaph

163k25 gold badges204 silver badges204 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

user1950221 Over a year ago

There is an exception, but I'm not sure how to repair it

Asaph Over a year ago

What is the value of ex->getMessage()?

kgautron · Accepted Answer · 2013-11-30 22:46:52Z

1

There probably is an exception in the code but you don't see it because of the catch with nothing inside. Add a log of the exception inside it, to reveal the exception and see the problem.

answered Nov 30, 2013 at 22:46

kgautron

8,34510 gold badges42 silver badges61 bronze badges

Collectives™ on Stack Overflow

Java Servlet & MySQL

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related