首先要获取jdbc文件

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

连接数据库（数据库要提前打完在写增删改查）

         Connection  connection=
DriverManager.getConnection("jdbc:mysql://localhost:3306/db_day11","root","root");

后面两个字段是账户和密码下载数据库设置的密码

Statement就是用来向数据库发送要执行的SQL语句的对象。

	Statement stmt = con.createStatement();

添加

  @Testpublic void insert() throws Exception {//1.获取连接对象，与数据库建立连接Connection con = getConnection();//2.获取sql执行对象Statement stmt = con.createStatement();//3.编写sqlString sql = "insert into user values(null,'zhaoliu', '789')";//4.执行sqlint i = stmt.executeUpdate(sql);System.out.println("插入成功，影响的行数："+i);//5.释放资源stmt.close();con.close();}

修改数据

   public static void main(String[] args) throws Exception {Class.forName("com.mysql.jdbc.Driver");Connection connection= DriverManager.getConnection("jdbc:mysql://localhost:3306/db_day11","root","root");Statement statement=connection.createStatement();int i1=statement.executeUpdate("update student set name='小伙'where id=3");System.out.println(i1);statement.close();connection.close();}

删除数据

 public static void fun2(String[] args) throws Exception {Class.forName("com.mysql.jdbc.Driver");Connection connection= DriverManager.getConnection("jdbc:mysql://localhost:3306/db_day11","root","root");Statement statement=connection.createStatement();ResultSet resultSet = statement.executeQuery(" delete from student where name='小伙'");statement.close();connection.close();}

重要的东西说三遍！

关闭数据要采用后行先关！！

关闭数据要采用后行先关！！

关闭数据要采用后行先关！！