2018-01-11 JDBC连接数据库代码

1.JDBC操作mysql数据库-增删改查

//查询数据
    @Test
    public void testQuery(){
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;
        try {
            //1.注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            //2.获取连接
            String url = "jdbc:mysql://localhost:3306/test";
            String user = "root";
            String password = "root";
            conn = DriverManager.getConnection(url, user, password);
            //3.获取执行SQL的statement
            stmt = conn.createStatement();
            //4.执行SQL
            String sql = "select * from user";
            stmt.execute(sql);
            rs = stmt.getResultSet();
            //5.处理结果
            while(rs.next()){
                System.out.println(rs.getString(1));
                System.out.println(rs.getString(2));
                System.out.println(rs.getString(3));
                System.out.println("---------------");
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            //6.释放资源
            release(rs,stmt,conn);
        }
    }

    //释放资源
    public static void release(ResultSet rs,Statement stmt,Connection conn){
        //6.释放资源
        if(rs != null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            rs = null;
        }
        if(stmt != null){
            try {
                stmt.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            stmt = null;
        }
        if(conn != null){
            try {
                conn.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            conn = null;
        }
    }
  }

2.JDBC操作Oracle数据库-增删改查

public void exeCuteQuery()throws Exception{
        Connection conn=null;
        //1.加载驱动
        Class.forName("oracle.jdbc.driver.OracleDriver");
        //2.建立连接
        conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","C##yujun","123456");
        //3.建立命令
        Statement st=conn.createStatement();
        //4.创建sql语句
        String sql="select * from student order by stuid,score desc";
        //执行命令获取结果集
        ResultSet rs=st.executeQuery(sql);
        System.out.println("姓名\t科目\t分数\t学号");
        while(rs.next()){
            System.out.print(rs.getString(1)+"\t");
            System.out.print(rs.getString(2)+"\t");
            System.out.print(rs.getInt(3)+"\t");
            System.out.println(rs.getInt(4)+"\t");
            
        }
        
    }