idea连接数据库实现增删改查

一，创建数据库中的表

1.创建表的sql语句

create table student(
stuID int,
stuName varchar(20),
stuAge int,
stuAdress varchar(40)
)

2.在表中插入数据

insert into student(stuID,stuName,stuAge,stuAdress) values("1","张三","18","河南")
insert into student(stuID,stuName,stuAge,stuAdress) values("2","小美","18","东北")
insert into student(stuID,stuName,stuAge,stuAdress) values("3","sim","18","英国")
insert into student(stuID,stuName,stuAge,stuAdress) values("4","sim","18","英国")

二.在idea中连接数据库实现增删改查

1.连接数据库

 private String driver="com.mysql.cj.jdbc.Driver";
   private  String url="jdbc:mysql://localhost:3306/student";
    private String username="root";
    private String password="root";

2.实现查询

 查询
    public  void query() throws Exception{
        //加载数据库的驱动
      Class.forName(driver);
        //使用驱动管理器来获得连接
        Connection con = DriverManager.getConnection(url, username, password);

        //使用Connection创建PreparedStatement预处理对象
        String sql="select * from student";
        PreparedStatement pstm = con.prepareStatement(sql);
        //使用PreparedStatement对象执行sql语句
        ResultSet re = pstm.executeQuery();
        //判断
        while (re.next()) {
            int stuId=re.getInt("stuID");
            String stuName=re.getString("stuName");
            int stuAge=re.getInt("stuAge");
            String stuAdress=re.getString("stuAdress");
            test01 student = new test01();
            student.setStuId(stuId);
            student.setStuName(stuName);
            student.setStuAge(stuAge);
            student.setStuAddress(stuAdress);
            System.out.println(student);
        }
        //资源回收
        if (re!=null){
            re.close();
        }
        if (pstm!=null){
            pstm.close();
        }
        if (con!=null){
            con.close();
        }
    }

3.实现增加

 @Test
    public  void increase() throws Exception{
        //加载数据库的驱动
        Class.forName(driver);
        //使用驱动管理器来获得连接
        Connection con = DriverManager.getConnection(url, username, password);

        //使用Connection创建PreparedStatement预处理对象
        String sql="insert into student(stuId,stuName,stuAge,stuAdress) values (?,?,?,?)";
        PreparedStatement pstm = con.prepareStatement(sql);
        test01 student = new test01();
        student.setStuId(5);
        student.setStuName("小明");
        student.setStuAge(20);
        student.setStuAddress("日本");
        pstm.setObject(1,student.stuId());
        pstm.setObject(2,student.stuName());
        pstm.setObject(3,student.stuAge());
        pstm.setObject(4,student.stuAdress());
        int n=pstm.executeUpdate();
        if (n>0){
            System.out.println("插入成功");
        }else {
            System.out.println("插入失败");
        }
        //资源回收
        if (pstm!=null){
            pstm.close();
        }
        if (con!=null){
            con.close();
        }


        //
    }

4.实现删除

@Test
    public void delete() throws Exception{
        //加载数据库的驱动
        Class.forName(driver);
        //使用驱动管理器来获得连接
        Connection con = DriverManager.getConnection(url, username, password);
        //3.编写SQL语句
        String sql="delete from student where stuId=?";
        //4.预处理SQL语句
        PreparedStatement pstm = con.prepareStatement(sql);
        pstm.setInt(1,1);
        int n=pstm.executeUpdate();
        if(n>0){
            System.out.println("删除成功");
        }else {
            System.out.println("删除失败");
        }
        //8.关闭资源
        if (pstm!=null){
            pstm.close();
        }
        if (con!=null){
            con.close();
        }
    }

5.实现修改

  改
    @Test
    public  void modify() throws Exception{
        //加载数据库的驱动
        Class.forName(driver);
        //使用驱动管理器来获得连接
        Connection con = DriverManager.getConnection(url, username, password);
        //3.编写SQL语句
        String sql="update student set stuName=?,stuAge=? where stuId=?";
        //4.预处理SQL语句
        PreparedStatement pstm = con.prepareStatement(sql);
       pstm.setObject(1,"王子龙");
       pstm.setObject(2,22);
       pstm.setObject(3,2);
        int n=pstm.executeUpdate();
        if(n>0){
            System.out.println("修改成功");
        }else {
            System.out.println("修改失败");
        }
        //8.关闭资源
        if (pstm!=null){
            pstm.close();
        }
        if (con!=null){
            con.close();
        }
    }
    }