JDBC练习五

/*
	执行DQL语句
*/

import java.sql.*;
import java.util.*;

public class JDBCTest05 {
    public static void main(String[] args) {
        // 1、注册驱动
        // 2、建立连接
        // 3、获取数据库操作对象
        // 4、执行sql语句
        // 5、获取查询结果集
        // 6、释放资源
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;

        try{
            ResourceBundle rb = ResourceBundle.getBundle("jdbc");
            String driver = rb.getString("driver");
            String url = rb.getString("url");
            String user = rb.getString("user");
            String password = rb.getString("password");

            Class.forName(driver);

            conn = DriverManager.getConnection(url,user,password);

            stmt = conn.createStatement();

            rs = stmt.executeQuery("select * from student");

            while(rs.next()){
				/*
				String studentid = rs.getString(1);
				String studentname = rs.getString(2);
				System.out.println(studentid + "," + studentname);
				*/

				/*
				// 按下标取出,程序不健壮
				String studentid = rs.getString("studentid");
				String studentname = rs.getString("studentname");
				System.out.println(studentid + "," + studentname);
				*/

				/*
				// 以指定的格式取出
				int studentid = rs.getInt(1);
				String studentname = rs.getString(2);
				System.out.println(studentid + "," + studentname);
				*/

                int studentid = rs.getInt("studentid");
                String studentname = rs.getString("studentname");
                System.out.println(studentid + "," + studentname);
            }

        } catch(Exception e){
            e.printStackTrace();
        }finally{
            if(rs != null){
                try{
                    rs.close();
                } catch (Exception e){
                    e.printStackTrace();
                }
            }
            if(stmt != null){
                try{
                    stmt.close();
                } catch (Exception e){
                    e.printStackTrace();
                }
            }
            if(conn != null){
                try{
                    conn.close();
                } catch (Exception e){
                    e.printStackTrace();
                }
            }
        }
    }
}

运行结果:

image-20210920191144745

Q.E.D.


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