简单数据库中更新数据出错 牛人们看下啊

Java code

package com.test.zhuce;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class Cshi {          public static void main(String[] args) throws ClassNotFoundException     {         Connection con = null;        Statement sql=null;         ResultSet rs=null;         String  uid="12092401";         String  sid="2221";            Class.forName( "sun.jdbc.odbc.JdbcOdbcDriver");            try {                con=DriverManager.getConnection("jdbc:odbc:lib","","");            } catch (SQLException e) {                                System.out.println("执行2");            }             String sqle="UPDATE yonghu set id1='"+sid+"' WHERE id="+"\'"+uid+"\'";                try {                    sql.executeUpdate(sqle);                } catch (SQLException e)                {                    System.out.println("执行");                }    }}

错误信息是：java.lang.NullPointerException

[解决办法]
Statement sql=null;

sql= conn.createStament