JDBC示例

Posted 2021-12-08 lsy-lsy

引用jdbc的jar包mysql-connector-java-5.1.47.jar，在eclipse中创建工程。

数据库字段为：

CREATE TABLE emp(
　　eid INT PRIMARY KEY,
　　ename VARCHAR(10),
　　price DOUBLE
);

 

  1 package jdbc;
  2 
  3 import java.sql.Connection;
  4 import java.sql.DriverManager;
  5 import java.sql.PreparedStatement;
  6 import java.sql.ResultSet;
  7 import java.sql.SQLException;
  8 import java.sql.Statement;
  9 
 10 
 11 public class JDBCTest {
 12     
 13     public static void jdbcDemoSelect(String driver,String url,String user,String password) throws Exception {
 14         
 15         //1.加载类驱动
 16         Class.forName(driver);
 17         Connection con = DriverManager.getConnection(url,user,password);
 18     
 19 //        if(!con.isClosed())
 20 //            System.out.println("succeeded connection to the database");
 21         
 22         //2.创建statement类对象，用来执行SQL语句
 23         Statement statement = con.createStatement();
 24         
 25         //SQL语句
 26         String sql = "select * from emp";    
 27         
 28         //3.ResultSet类，用来存放获取的结果集
 29         ResultSet set = statement.executeQuery(sql);
 30         
 31         String eid=null,ename=null,price=null;
 32         
 33         while(set.next()) {
 34             eid = set.getString("eid");
 35             ename = set.getString("ename");
 36             price = set.getString("price");
 37             
 38             System.out.println(eid+"\t"+ename+"\t"+price);
 39         }
 40         
 41     }
 42     
 43     public static void jdbcDemoUpdate(String driver,String url,String user,String password) throws Exception {
 44         
 45         //1.加载类驱动
 46         Class.forName(driver);
 47         Connection con = DriverManager.getConnection(url,user,password);
 48         
 49         String sql = "update emp set price=? where eid=?";
 50         
 51         //2。传值调用方法
 52         PreparedStatement ps = con.prepareStatement(sql);
 53         ps.setDouble(1, 3.6);
 54         ps.setDouble(2, 1101);
 55         
 56         //执行结果
 57         ps.executeUpdate();
 58         
 59     }
 60 
 61     public static void jdbcDemoInsert(String driver,String url,String user,String password) throws Exception {
 62         
 63         Class.forName(driver);
 64         Connection con = DriverManager.getConnection(url,user,password);
 65         
 66         String sql = "INSERT INTO emp VALUES(?,?,?)";
 67         
 68         PreparedStatement ps = con.prepareStatement(sql);
 69         ps.setInt(1, 1108);
 70         ps.setString(2, "牛奶");
 71         ps.setDouble(3, 3.0);
 72         
 73         ps.executeUpdate();
 74         
 75     }
 76     
 77     public static void jdbcDemoDelete(String driver,String url,String user,String password) throws Exception {
 78         
 79         Class.forName(driver);
 80         Connection con = DriverManager.getConnection(url,user,password);
 81         
 82         String sql = "DELETE FROM emp WHERE eid=?";
 83         
 84         PreparedStatement ps = con.prepareStatement(sql);
 85         ps.setInt(1, 1108);
 86         
 87         ps.executeUpdate();
 88         
 89     }
 90     
 91     public static void main(String[] args) throws Exception {
 92         
 93         //驱动名
 94         String driver = "com.mysql.jdbc.Driver";
 95         //url指向要访问的数据库my_DB
 96         String url = "jdbc:mysql://localhost:3306/my_DB";
 97         //mysql用户名
 98         String user = "root";
 99         //密码
100         String password = "123456";
101         
102 //        jdbcDemoInsert(driver,url,user,password);
103         
104         jdbcDemoDelete(driver,url,user,password);
105         
106     }
107 
108 }