<?php
$createTablesMySql = array(
    "
        CREATE TABLE IF NOT EXISTS grades (
            id INT AUTO_INCREMENT PRIMARY KEY,
            student_id INT NOT NULL,
            teacher_id INT NOT NULL,
            class_id INT DEFAULT NULL,
            subject VARCHAR(100) NOT NULL,
            grade VARCHAR(10) NOT NULL,
            comment TEXT NULL,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
    "


);