数据库连接的步骤以及SQL的处理结果

1、注册连接

//适用于mysql 8.0以后的数据库连接 
Class.forName("com.mysql.cj.jdbc.Driver");


//适用于mysql 8.0之前的数据库连接 
Class.forName("com.mysql.jdbc.Driver");

2、获取驱动

//输入自己想要连接数据库里的表，选择账号和密码 
Connection  conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db1","root", "1357");

3、获取执行者对象

Statement st = conn.createStatement();

4、执行sql语句，并接受返回结果

//查询所有  
 String sql = "select * from student";
//根据id查询

//输出返回结果
ResultSet rs = stat.executeQuery(sql);

5、处理结果

//遍历表
//这里也是Array接口格式，不用的话，在findall的做后要进行格式的转换
public static ArrayList<Student> list = new ArrayList<>();
while (rs.next()) {
                Integer sid = rs.getInt("sid");
                String name = rs.getString("name");
                int age = rs.getInt("age");
                Date birthday = rs.getDate("birthday");
                Student stu = new Student();
                stu.setAge(sid);
                stu.setName(name);
                stu.setAge(age);
                stu.setBirthday(birthday);
                list.add(stu);
            }

6、释放资源

conn.close();
st.close();
rs.close();

结果集的处理（增删改查）

1.进行遍历 查询所有数据的时候使用

 while (rs.next()) {
                Integer sid = rs.getInt("sid");
                String name = rs.getString("name");
                int age = rs.getInt("age");
                Date birthday = rs.getDate("birthday");
                Student stu = new Student();
                stu.setAge(sid);
                stu.setName(name);
                stu.setAge(age);
                stu.setBirthday(birthday);
                list.add(stu);
            }

2.进行查询单个数据，根据id

Integer sid = rs.getInt("sid");
String name = rs.getString("name");
Integer age = rs.getInt("age");
Date birthday = rs.getDate("birthday");
//封装Student对象
stu.setSid(sid);
stu.setName(name);
stu.setAge(age);
stu.setBirthday(birthday);

3.进行插入数据的结果集

//转换date的格式 
java.util.Date date = stu.getBirthday();
//简单数据的格式化，转换为自己想要的格式
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            String birthday = sdf.format(date);
            String sql = "insert into student  values('" + stu.getSid() + "','" 
                        + stu.getName() + "'," +"'" + stu.getAge() + "','"
                         + birthday + "')";
            int result = st.executeUpdate(sql);
            return result;

4、进行数据的增加

 //sql语句
            java.util.Date date = stu.getBirthday();
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            String birthday = sdf.format(date);
            String sql = "insert into student  values('" + stu.getSid() + "','" + stu.getNam                          e() + "'," +
                    "'" + stu.getAge() + "','" + birthday + "')";
            int result2 = st.executeUpdate(sql);

            return result2;

5、进行数据的删除

String sql = "DELETE FROM student WHERE sid='"+id+"'";
result = stat.executeUpdate(sql);

6、进行数据的更新

Date d = stu.getBirthday();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String birthday = sdf.format(d);
String sql = "UPDATE student SET
sid='"+stu.getSid()+"',name='"+stu.getName()+"',age='"+stu.getAge()+"',birthday=
'"+birthday+"' WHERE sid='"+stu.getSid()+"'";
result = stat.executeUpdate(sql);