classes.php

<?php
    class Stundent {
        private $student_id = NULL;
        private $first_name;
        private $last_name;
        private $gender;
        private $email;
        private $birth_date;
        private $specialty;
        private $spec_id;
        private $exam_results = [];
        public function addToDB($db_conn, $exams) {
            $sqlquery = "INSERT INTO students (first_name, last_name, email, gender, birth_date, spec_id)
                                        VALUES ('{$this->first_name}', '{$this->last_name}', '{$this->email}',
                                    '{$this->gender}', '{$this->birth_date}', {$this->spec_id})";
            if (!mysqli_query($db_conn,$sqlquery)) {
                echo 'Error: Cannot add to database</br>';
            };
            $res = mysqli_query($db_conn, "SELECT student_id FROM students
                                                    WHERE first_name = '{$this->first_name}' AND last_name = '{$this->last_name}' AND email = '{$this->email}'");
            $row = mysqli_fetch_assoc($res);
            $this->student_id = $row["student_id"];
            foreach ($exams as $exam_id => $exam_name) {
                $sqlquery = "INSERT INTO exam_results (student_id, exam_id, exam_points)
                                            VALUES ('{$this->student_id}', {$exam_id}, '{$this->exam_results[$exam_id][1]}')";
                $res = mysqli_query($db_conn, $sqlquery);
            }
        }
        public function getFromDB($db_conn, $exams) {
            $res = mysqli_query($db_conn, "SELECT gender, birth_date, spec_id, student_id FROM students
            WHERE first_name = '{$this->first_name}' AND last_name = '{$this->last_name}' AND email = '{$this->email}'");
            $row = mysqli_fetch_assoc($res);
            $this->gender=$row["gender"];
            $this->birth_date=$row["birth_date"];
            $this->spec_id = $row["spec_id"];
            $this->student_id = $row["student_id"];
            $res = mysqli_query($db_conn, "SELECT name FROM specialties WHERE spec_id = {$this->spec_id}");
            $row = mysqli_fetch_assoc($res);
            $this->specialty = $row["name"];
            foreach ($exams as $exam_id => $exam_name) {
                $res = mysqli_query($db_conn, "SELECT exam_points FROM exam_results WHERE student_id = {$this->student_id} AND exam_id = {$exam_id}");
                $row = mysqli_fetch_assoc($res);
                $ex = [$exam_name, $row['exam_points']];
                $this->exam_results[$exam_id] = $ex;
            }
        }

        public function getFromDBAll($db_conn, $exams) {
            $res = mysqli_query($db_conn, "SELECT * FROM students");
            $row = mysqli_fetch_assoc($res);
            while ($row) {
                $this->student_id = $row["student_id"];
                $this->first_name = $row["first_name"];
                $this->last_name = $row["last_name"];
                $this->email = $row["email"];
                $this->gender=$row["gender"];
                $this->birth_date=$row["birth_date"];
                $this->spec_id = $row["spec_id"];
                $res = mysqli_query($db_conn, "SELECT name FROM specialties WHERE spec_id = {$this->spec_id}");
                $row = mysqli_fetch_assoc($res);
                $this->specialty = $row["name"];
                foreach ($exams as $exam_id => $exam_name) {
                    $res = mysqli_query($db_conn, "SELECT exam_points FROM exam_results WHERE student_id = {$this->student_id} AND exam_id = {$exam_id}");
                    $row = mysqli_fetch_assoc($res);
                    $ex = [$exam_name, $row['exam_points']];
                    $this->exam_results[$exam_id] = $ex;
                }
                $this->printStudent();
            }
        }

        public function saveExamResults($exam_id, $exam_name, $exam_points) {
            $ex = [];
            array_push($ex, $exam_name, $exam_points);
            $this->exam_results[$exam_id] = $ex;
        }

        public function printStudent () {
            //foreach ($this->exams as $exam_id => $exam_name) {
            //}
            echo $this->first_name . " " . $this->last_name . " " . $this->email . " " . $this->gender .
            " " . $this->birth_date . " " . $this->specialty;
        }

        public function __construct($first_name, $last_name, $email,
                                                                $gender, $birth_date, $specialty, $specialties) {
            $this->first_name = $first_name;
            $this->last_name = $last_name;
            $this->email = $email;
            $this->gender = $gender;
            $this->birth_date = $birth_date;
            if ($specialty) {
                $this->specialty = $specialty;
                $flip_specialties = array_flip($specialties);
                $this->spec_id = $flip_specialties[$specialty];
            }
        }
    }