CREATE TABLE IF NOT EXISTS `teams` (
  `id` INT AUTO_INCREMENT PRIMARY KEY,
  `name` VARCHAR(255) NOT NULL UNIQUE
);

CREATE TABLE IF NOT EXISTS `tournaments` (
  `id` INT AUTO_INCREMENT PRIMARY KEY,
  `name` VARCHAR(255) NOT NULL,
  `start_date` DATETIME DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE IF NOT EXISTS `matches` (
  `id` INT AUTO_INCREMENT PRIMARY KEY,
  `tournament_id` INT NOT NULL,
  `round` INT NOT NULL,
  `team1_id` INT,
  `team2_id` INT,
  `winner_id` INT,
  FOREIGN KEY (`tournament_id`) REFERENCES `tournaments`(`id`) ON DELETE CASCADE,
  FOREIGN KEY (`team1_id`) REFERENCES `teams`(`id`) ON DELETE SET NULL,
  FOREIGN KEY (`team2_id`) REFERENCES `teams`(`id`) ON DELETE SET NULL,
  FOREIGN KEY (`winner_id`) REFERENCES `teams`(`id`) ON DELETE SET NULL
);