Okay, so this would be my starting point (subject to change without notice if I think more about it), generated with MySQL Workbench:
[ATTACH]15755[/ATTACH]
-- -----------------------------------------------------
-- Table `mydb`.`user`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`user` (
`user_id` INT NOT NULL ,
PRIMARY KEY (`user_id`) )
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`team`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`team` (
`team_id` INT NOT NULL ,
`user_id` INT NULL ,
PRIMARY KEY (`team_id`) ,
INDEX `user_id_idx` (`user_id` ASC) ,
CONSTRAINT `user_id`
FOREIGN KEY (`user_id` )
REFERENCES `mydb`.`user` (`user_id` )
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`player`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`player` (
`player_id` INT NOT NULL ,
PRIMARY KEY (`player_id`) )
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`player_to_team`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`player_to_team` (
`player_id` INT NOT NULL ,
`team_id` INT NOT NULL ,
INDEX `player_fk_idx` (`player_id` ASC) ,
INDEX `team_fk_idx` (`team_id` ASC) ,
PRIMARY KEY (`player_id`) ,
UNIQUE INDEX `player_team` (`player_id` ASC, `team_id` ASC) ,
CONSTRAINT `player_fk`
FOREIGN KEY (`player_id` )
REFERENCES `mydb`.`player` (`player_id` )
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `team_fk`
FOREIGN KEY (`team_id` )
REFERENCES `mydb`.`team` (`team_id` )
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
The attachments of this post were removed during the platform migration in 2018
