数据库基础知识

几种数据库连接方式优缺点比较

     

能成功连接mysql的jdbc：

  Class.forName("com.mysql.jdbc.Driver");

  Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","123456");

  Statement stmt = conn.createStatement();

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

import java.io.File;

import java.io.IOException;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import org.jsoup.Jsoup;

import org.jsoup.nodes.Document;

import org.jsoup.nodes.Element;

import org.jsoup.select.Elements;

public class HttpUtils {

       public static void main(String []args) {

             

             java.sql.Connection con = null;

             

             String url = "jdbc:mysql://localhost:3306/sq_cqzgd?"

                + "user=root&password=123456&useUnicode=true&characterEncoding=UTF8";

             

             ResultSet rs = null;

             java.sql.Statement stmt=null;

             

             try{

               //先加载驱动

             Class.forName("com.mysql.jdbc.Driver");

             }catch(ClassNotFoundException e){

                    System.out.println("找不到驱动程序类，加载驱动失败!");

                    e.printStackTrace();

             }

                    

            try{  

               //创建数据库的连接

            con =    java.sql.DriverManager.getConnection(url); 

            }catch(SQLException se){  

               System.out.println("数据库连接失败!");  

               se.printStackTrace();  

            }   

           

            try{

                    //对数据库进行查询操作，返回时一个对象

               stmt = con.createStatement();

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

               while(rs.next()) {

                        System.out.print(rs.getInt("articleId") + "   ");

                        System.out.print(rs.getInt("userId") + "   ");

                        System.out.println(rs.getString("articleTitle") + "   ");

                       }

            }catch(SQLException e){

               System.out.println("数据库操作失误!");

               e.printStackTrace();

            }

           

            try {

                 if(rs != null) {

                  rs.close();

                  rs = null;

                 }

                 if(stmt != null) {

                  stmt.close();

                  stmt = null;

                 }

                 if(con != null) {

                  con.close();

                  con = null;

                 }

                } catch(Exception e) {

                 System.out.println("数据库关闭错误");

                 e.printStackTrace();

                }

    }

}