CREATE TABLE IF NOT EXISTS `platform_lines` (
    `id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
    `platformId` INT UNSIGNED NOT NULL,
    `lineId` INT UNSIGNED NOT NULL,
    `directionId` TINYINT UNSIGNED NOT NULL DEFAULT 0,
    `orderInLine` SMALLINT UNSIGNED NOT NULL,

    PRIMARY KEY (id),
    UNIQUE KEY uq_platform_line_dir (platformId, lineId, directionId),
    UNIQUE KEY uq_line_dir_order (lineId, directionId, orderInLine),
    INDEX idx_pl_line (lineId),

    CONSTRAINT fk_pl_platform FOREIGN KEY (platformId)
        REFERENCES platforms(id) ON DELETE CASCADE,
    CONSTRAINT fk_pl_line FOREIGN KEY (lineId)
        REFERENCES `lines`(id) ON DELETE CASCADE
);