JDBC操作数据库，比如修改电商数据库中的分类的id，让各商品随机

package CRM;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;



public class JDBC {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        //1、加载驱动
        Class.forName("com.mysql.jdbc.Driver");
        
        //2、建立连接
        String url01="jdbc:mysql://localhost:13306/ecshop?"
                + "user=root&password=123456&allowMultiQuerises=true;";
         
        Connection con=null;
        try {
            con=DriverManager.getConnection(url01);
            System.out.println("建立成功");
        } catch (SQLException e) {
            System.out.println("建立失败");
        }
        
        
        //3、操作句柄
        String sql="select goods_name from ecs_goods where goods_name like '测试%';",
                sql1="select cat_id from ecs_category;";
                //sql2="update ecs_goods set cat_id =${catid}  where goods_name";
        Statement stmt=null,stmt1=null,stmt2=null;
        try {
            stmt=con.createStatement();    
            stmt1=con.createStatement();
            stmt2=con.createStatement();
        } catch (SQLException e) {    
        }
        
        
        //进行数据库查询
        ResultSet rs=stmt.executeQuery(sql),rs1=stmt1.executeQuery(sql1);
        
        int n = rs1.getMetaData().getColumnCount(),n1 = rs.getMetaData().getColumnCount();
        //(1)获取商品分类
        String s="";
        while (rs1.next()){
            String s1=rs1.getString(n);
            if (s==""){
                s=s1;
            }else{
                s=s+","+s1;
            }
        
        }
        System.out.println(s);
        String [] s1= s.split(","); 
        
        //(2)获取需要修改的商品
        s="";
        
        while (rs.next()){
         String s2=rs.getString(n);
            if (s==""){
                s=s2;
            }else{
                s=s+","+s2;
            }
        
        }
        
        String [] s2= s.split(","); 
        System.out.println(s2[1]);
        
        //(3)随机修改商品的分类
        for(int i = 0 ; i<s2.length;i++){
            
            stmt2.executeUpdate("update ecs_goods set cat_id ='"+s1[(int) (Math.random()*s1.length)] 
                    +"'where goods_name='"+s2[i]+"';");
            
        }                
        
        
        
    }
}