JDBC示例

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
);

package jdbc;

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


public class JDBCTest {
    
    public static void jdbcDemoSelect(String driver,String url,String user,String password) throws Exception {
        
        //1.加载类驱动
        Class.forName(driver);
        Connection con = DriverManager.getConnection(url,user,password);
    
//        if(!con.isClosed())
//            System.out.println("succeeded connection to the database");
        
        //2.创建statement类对象，用来执行SQL语句
        Statement statement = con.createStatement();
        
        //SQL语句
        String sql = "select * from emp";    
        
        //3.ResultSet类，用来存放获取的结果集
        ResultSet set = statement.executeQuery(sql);
        
        String eid=null,ename=null,price=null;
        
        while(set.next()) {
            eid = set.getString("eid");
            ename = set.getString("ename");
            price = set.getString("price");
            
            System.out.println(eid+"	"+ename+"	"+price);
        }
        
    }
    
    public static void jdbcDemoUpdate(String driver,String url,String user,String password) throws Exception {
        
        //1.加载类驱动
        Class.forName(driver);
        Connection con = DriverManager.getConnection(url,user,password);
        
        String sql = "update emp set price=? where eid=?";
        
        //2。传值调用方法
        PreparedStatement ps = con.prepareStatement(sql);
        ps.setDouble(1, 3.6);
        ps.setDouble(2, 1101);
        
        //执行结果
        ps.executeUpdate();
        
    }

    public static void jdbcDemoInsert(String driver,String url,String user,String password) throws Exception {
        
        Class.forName(driver);
        Connection con = DriverManager.getConnection(url,user,password);
        
        String sql = "INSERT INTO emp VALUES(?,?,?)";
        
        PreparedStatement ps = con.prepareStatement(sql);
        ps.setInt(1, 1108);
        ps.setString(2, "牛奶");
        ps.setDouble(3, 3.0);
        
        ps.executeUpdate();
        
    }
    
    public static void jdbcDemoDelete(String driver,String url,String user,String password) throws Exception {
        
        Class.forName(driver);
        Connection con = DriverManager.getConnection(url,user,password);
        
        String sql = "DELETE FROM emp WHERE eid=?";
        
        PreparedStatement ps = con.prepareStatement(sql);
        ps.setInt(1, 1108);
        
        ps.executeUpdate();
        
    }
    
    public static void main(String[] args) throws Exception {
        
        //驱动名
        String driver = "com.mysql.jdbc.Driver";
        //url指向要访问的数据库my_DB
        String url = "jdbc:mysql://localhost:3306/my_DB";
        //mysql用户名
        String user = "root";
        //密码
        String password = "123456";
        
//        jdbcDemoInsert(driver,url,user,password);
        
        jdbcDemoDelete(driver,url,user,password);
        
    }

}