Database

I don't know how to write this PL/SQL in oracle, thanks for your advice.
Because the amount of data in the table is large, it is not suitable to find the max PDate and then compare it from the source table.

Table data:
Process	 	 PDate	 	 	 	 	Status
100	 	 	 2022/05/21 19:58:03	0
100	 	 	 2022/05/22 07:01:00	0
100	 	 	 2022/05/22 13:01:10	1
101	 	 	 2022/05/22 08:23:39	0
101	 	 	 2022/05/22 10:17:39	0
101	 	 	 2022/05/22 17:49:39	1
102	 	 	 2022/05/22 13:14:48	0

Requirement: Get the status of the last record of different processes on 2022/05/22
Select result:
Process	 	 PDate			 	 	 Status
100	 	 	 2022/05/22 13:01:10	 1
101	 	 	 2022/05/22 17:49:39	 1
102	 	 	 2022/05/22 13:14:48	 0

  start    |    end
2022-03-01 | 2022-04-10
2021-12-01 | 2022-03-11
2022-01-01 | 2022-04-05
...

My database tbl_user has the following columns :

    | User_id | Upline | Right_id | Left_id |
    +--------+---------+----------+---------+
    | 1      | 0       |   4      | 7       |
    | 2      | 0       |   6      | 5       |
    | 3      | 0       |   0      | 0       |
    | 4      | 1       |   0      | 0       |
    | 5      | 2       |   0      | 0       |
    | 6      | 2       |   0      | 0       |
    | 7      | 1       |   0      | 0       |
    | 8      | 0       |   0      | 0       |
    | 9      | 0       |   0      | 0       |
    | 10     | 0       |   0      | 0       |  
    +--------+---------+----------+---------+

    $user_id = 2;
    
    $user_tree = $this->getAllRec("u.user_id",  
    "tbl_user u",
    "WHERE u.Upline = '".$user_id."'
    ORDER BY Right_id ASC");
    
    print_r($user_tree);

I want the array `$user_tree` to hold (user_id 5) first, then (user_id 6), how to do that?

I want to print **Left_id** first, then only print **Right_id**. May I know how to do it?

Do I need to use left join or use another query?

public class Teacher
{
        public string Id{ get; set; }
        public string Name{ get; set; }
        public string TeacherFilter{ get; set; }
        ...
}

public class Student
{
        public string Id{ get; set; }
        public string Name{ get; set; }
        public string StudentFilter{ get; set; }
        public string TeacherId{ get; set; }
        ...
}

public class TeacherStudents
{
        public string Id{ get; set; } -- from teacher
        public string Name{ get; set; } -- from teacher
        public IEnumerable<Student> Students{get;set;}
}

public class TeacherStudents
{
        public string Id{ get; set; } -- from teacher
        public string Name{ get; set; } -- from teacher
        public IEnumerable<Student> Student{get;set;}
}

public class TeacherStudent
{
        public string Id{ get; set; } -- from teacher
        public string Name{ get; set; } -- from teacher
        ...
        public Student Student{get;set;}
}

Get(string TeacherFilter,string StudentFilter).

var query = teacherCollection.Aggregate().Match(x => x.TeacherFilter== TeacherFilter); //filter teach
var query1 = query
.Lookup<Teacher, Student, TeacherStudent>(studentCollection, t => t.Id, s => s.TeacherId, l => l.Student)
.Unwind(x => x.Student, new AggregateUnwindOptions<TeacherStudent>())
.Match(x => x.StudentFilter== StudentFilter) //filter student