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

 1 package CRM;
 2 
 3 import java.sql.Connection;
 4 import java.sql.DriverManager;
 5 import java.sql.ResultSet;
 6 import java.sql.SQLException;
 7 import java.sql.Statement;
 8 
 9 
10 
11 public class JDBC {
12     public static void main(String[] args) throws ClassNotFoundException, SQLException {
13         //1、加载驱动
14         Class.forName("com.mysql.jdbc.Driver");
15         
16         //2、建立连接
17         String url01="jdbc:mysql://localhost:13306/ecshop?"
18                 + "user=root&password=123456&allowMultiQuerises=true;";
19          
20         Connection con=null;
21         try {
22             con=DriverManager.getConnection(url01);
23             System.out.println("建立成功");
24         } catch (SQLException e) {
25             System.out.println("建立失败");
26         }
27         
28         
29         //3、操作句柄
30         String sql="select goods_name from ecs_goods where goods_name like '测试%';",
31                 sql1="select cat_id from ecs_category;";
32                 //sql2="update ecs_goods set cat_id =${catid}  where goods_name";
33         Statement stmt=null,stmt1=null,stmt2=null;
34         try {
35             stmt=con.createStatement();    
36             stmt1=con.createStatement();
37             stmt2=con.createStatement();
38         } catch (SQLException e) {    
39         }
40         
41         
42         //进行数据库查询
43         ResultSet rs=stmt.executeQuery(sql),rs1=stmt1.executeQuery(sql1);
44         
45         int n = rs1.getMetaData().getColumnCount(),n1 = rs.getMetaData().getColumnCount();
46         //(1)获取商品分类
47         String s="";
48         while (rs1.next()){
49             String s1=rs1.getString(n);
50             if (s==""){
51                 s=s1;
52             }else{
53                 s=s+","+s1;
54             }
55         
56         }
57         System.out.println(s);
58         String [] s1= s.split(","); 
59         
60         //(2)获取需要修改的商品
61         s="";
62         
63         while (rs.next()){
64          String s2=rs.getString(n);
65             if (s==""){
66                 s=s2;
67             }else{
68                 s=s+","+s2;
69             }
70         
71         }
72         
73         String [] s2= s.split(","); 
74         System.out.println(s2[1]);
75         
76         //(3)随机修改商品的分类
77         for(int i = 0 ; i<s2.length;i++){
78             
79             stmt2.executeUpdate("update ecs_goods set cat_id ='"+s1[(int) (Math.random()*s1.length)] 
80                     +"'where goods_name='"+s2[i]+"';");
81             
82         }                
83         
84         
85         
86     }
87 }

 

转载于:https://www.cnblogs.com/ceshixuexi/p/7277067.html