db select

no argument: Statement
one or more argument: PreparedStatement

public class Outer {
    public static void main(String[] args) throws Exception{
        Connection con = DriverManager.getConnection("jdbc:derby://localhost:1527/data/Sample");
        try(con) {
            System.out.println(con);
            String sql = "select * from firsttable where id<=?";
            PreparedStatement ps = con.prepareStatement(sql);
            ps.setInt(1,20);
            ResultSet rs = ps.executeQuery();
            ResultSetMetaData md = ps.getMetaData();
            int columnCount = md.getColumnCount();
            System.out.println("col count : " + columnCount);
            
            try(rs) {
                int colIndex = 0;
                while(rs.next()){
                    
                    System.out.print(rs.getString("ID") + ":");
                    System.out.println(rs.getString("NAME"));
                    for(int i=0;i<columnCount;i++) {
                        colIndex = i + 1;
                        System.out.println(" "+ md.getTableName(colIndex) + ":" + 
                                md.getColumnName(colIndex) + ":" +
                                rs.getString(colIndex));
                    }
                }
            }
        }
    }
}

org.apache.derby.client.net.NetConnection@17d0685f
org.apache.derby.client.net.NetConnection@17d0685f
col count : 2
10:TEN
 FIRSTTABLE:ID:10
 FIRSTTABLE:NAME:TEN
20:TWENTY
 FIRSTTABLE:ID:20
 FIRSTTABLE:NAME:TWENTY