我无法使用Java连接到数据库

Question

Connection conn = null;
Statement stmt=null;
ResultSet rset=null;
String jdbc_url="jdbc:oracle:thin:hr/hr@bassam-desktop:1521:XE";
String query="";
try
{
    DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
    conn=DriverManager.getConnection(jdbc_url);
    stmt=(Statement) conn.createStatement();
    query="select first_name" +"from employees"+"where employeed_id=100";
    rset=stmt.executeQuery(query);
    System.out.println(rset.getString(1));


}
catch(SQLException | NumberFormatException e)
        {
            System.out.println("result error");
        }
finally{
    try{
        rset.close();
        stmt.close();
        conn.close();

    }
    catch(Exception e)
    {
        System.out.println("Error in closing");
    }
}

I'm getting both errors in the results window, what is the problem? hr password is correct, my host name is correct, isn't it the one you get from "Computer Name" after you right click on "My Computer" in windows xp ?

Edit: After using e.getMessage(), i got this..

result error, ResultSet.next was not called

Answer 1

The error message of the exception, that you have put in the comments, tells you what's wrong:

result error, ResultSet.next was not called

You forgot to call ResultSet.next() before accessing the first row of the result set:

if (rset.next()) {
    System.out.println(rset.getString(1));
}

Answer 2

Because you're using Netbeans IDE, you can try connecting with their built in tool . That should help you get the jdbc_url right (which is almost certainly the problem). Also, don't forget to download and include in your classpath the ojdbc6.jar (which would definitely be the problem if you're not including it).

Answer 3

The e variable represent the exception. try to print the e.getMessage() or print the stack trace with e.printStackTrace() to understand better the problem.

Answer 4

 ResultSet rset = stmt.executeQuery();
 while(rset.next()){
     //Code that works with results
 }