JAVA操作数据库

版权声明：均是学习笔记、心得，如有冒犯，请指出，会及时处理。 https://blog.csdn.net/u013355826/article/details/81974706

任务：用JAVA添加JDBC方式返回数据库中的所有数据。

直接在类中写主函数，实现：1.注册驱动；2.建立连接；3.建立 statement;4.执行sql语句；5.输出结果；6.释放资源

package chape01;

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

public class JDBCDemo {
	
	public static void main(String[] args){
		
		String driver = "com.mysql.jdbc.Driver";
		String  url = "jdbc:mysql://<IP>:<port>/<DBbase>?useUnicode=true&characterEncoding=utf-8&useSSL=false";
		String user = "root";
		String password = "123456";
		String sql = "select * from mytable";
		ResultSet res  = null;
		Statement state = null;
		Connection Conn = null;
		
		try{
			//1.注册
			Class.forName(driver);
			//2.连接
			Conn = (Connection)DriverManager.getConnection(url, user, password);
			
			//3.建立statement
			state = Conn.createStatement();

			//4.执行sql语句
			res = state.executeQuery(sql);
			
			//5.输出结果
			while(res.next()){
				
				System.out.print(res.getInt("id")+"|");
				System.out.print(res.getString("name")+"|");
				System.out.println();
				
			}
			
		}catch(Exception e){
			
			e.printStackTrace();
		}finally{
			//6. 关闭资源
			try{
				if(res != null){
					
					res.close();
				}
			}catch(SQLException e){
				
				e.printStackTrace();
			}finally{
				
				res = null;
				System.out.println("res 资源释放！");
			}
			
		}
		try{
			if(state != null){
				
				state.close();
			}
		}catch(SQLException e){
			
			e.printStackTrace();
		}finally{
			
			state = null;
			System.out.println("state 资源释放！");
		}
		try{
			if(Conn != null){
				
				Conn.close();
			}
		}catch(SQLException e){
			
			e.printStackTrace();
		}finally{
			
			Conn = null;
			System.out.println("Conn 资源释放！");
		}
	}
		
}