How to model multiple members of groups? - mysql

Question

How should one model multiple members of groups? Let me give an example.
I have people, houses, and household items.
All houses are owned by a single person and a person can own more than one house.
All household items are located in a single house, and are owned by the owner of the house. For my particular situation, I would also like a incremental counter for all household items owned by a given person.
In addition, while all household items share some properties, they also have some properties based on the type of household item they are. Assume there are only a few types of household items such as waterbeds, televisions, and refrigerators. Note that it must also be possible to link a household item to another table (for instance, otherPeopleInterestedInBuyingAHouseholdItem must have a foreign key to household items regardless of the type of household item).
So, houses are the group, and householdItems are members of that group.
How should this be modeled? Two possibilities are below. Is one better than the other given the above rules? I recognize that the first option with houses composite incrementing primary key doesn't play nice with InnoDB, however, can be implemented with triggers/etc which is acceptable. Or maybe a third option which is better?
-- MySQL Script generated by MySQL Workbench
-- 02/16/17 16:01:38
-- Model: New Model Version: 1.0
SET #OLD_UNIQUE_CHECKS=##UNIQUE_CHECKS, UNIQUE_CHECKS=0;
SET #OLD_FOREIGN_KEY_CHECKS=##FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0;
SET #OLD_SQL_MODE=##SQL_MODE, SQL_MODE='TRADITIONAL,ALLOW_INVALID_DATES';
-- -----------------------------------------------------
-- Schema mydb
-- -----------------------------------------------------
CREATE SCHEMA IF NOT EXISTS `mydb` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci ;
USE `mydb` ;
-- -----------------------------------------------------
-- Table `mydb`.`people`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`people` (
`idpeople` INT NOT NULL AUTO_INCREMENT,
`name` VARCHAR(45) NOT NULL,
`age` INT NOT NULL,
PRIMARY KEY (`idpeople`))
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`houses`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`houses` (
`idhouses` INT NOT NULL AUTO_INCREMENT,
`people_idpeople` INT NOT NULL,
`address` VARCHAR(45) NOT NULL,
`square_feet` INT NOT NULL,
PRIMARY KEY (`idhouses`),
INDEX `fk_houses_people1_idx` (`people_idpeople` ASC),
CONSTRAINT `fk_houses_people1`
FOREIGN KEY (`people_idpeople`)
REFERENCES `mydb`.`people` (`idpeople`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`houseHoldItems`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`houseHoldItems` (
`idhouseHoldItems` INT NOT NULL AUTO_INCREMENT,
`houses_idhouses` INT NOT NULL,
`value` DECIMAL(6,2) NOT NULL,
`dateBought` DATETIME NOT NULL,
PRIMARY KEY (`idhouseHoldItems`, `houses_idhouses`),
INDEX `fk_houseHoldItems_houses_idx` (`houses_idhouses` ASC),
CONSTRAINT `fk_houseHoldItems_houses`
FOREIGN KEY (`houses_idhouses`)
REFERENCES `mydb`.`houses` (`idhouses`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`waterBeds`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`waterBeds` (
`houseHoldItems_idhouseHoldItems` INT NOT NULL,
`houseHoldItems_houses_idhouses` INT NOT NULL,
`gallonsWaterSize` INT NOT NULL,
PRIMARY KEY (`houseHoldItems_idhouseHoldItems`, `houseHoldItems_houses_idhouses`),
CONSTRAINT `fk_waterBeds_houseHoldItems1`
FOREIGN KEY (`houseHoldItems_idhouseHoldItems` , `houseHoldItems_houses_idhouses`)
REFERENCES `mydb`.`houseHoldItems` (`idhouseHoldItems` , `houses_idhouses`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`televisions`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`televisions` (
`houseHoldItems_idhouseHoldItems` INT NOT NULL,
`houseHoldItems_houses_idhouses` INT NOT NULL,
`screenSize` INT NOT NULL,
`brandName` VARCHAR(45) NOT NULL,
PRIMARY KEY (`houseHoldItems_idhouseHoldItems`, `houseHoldItems_houses_idhouses`),
CONSTRAINT `fk_televisions_houseHoldItems1`
FOREIGN KEY (`houseHoldItems_idhouseHoldItems` , `houseHoldItems_houses_idhouses`)
REFERENCES `mydb`.`houseHoldItems` (`idhouseHoldItems` , `houses_idhouses`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`refrigerators`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`refrigerators` (
`houseHoldItems_idhouseHoldItems` INT NOT NULL,
`houseHoldItems_houses_idhouses` INT NOT NULL,
`icecubeCapacity` INT NOT NULL,
`color` VARCHAR(45) NOT NULL,
PRIMARY KEY (`houseHoldItems_idhouseHoldItems`, `houseHoldItems_houses_idhouses`),
CONSTRAINT `fk_refrigerators_houseHoldItems1`
FOREIGN KEY (`houseHoldItems_idhouseHoldItems` , `houseHoldItems_houses_idhouses`)
REFERENCES `mydb`.`houseHoldItems` (`idhouseHoldItems` , `houses_idhouses`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
SET SQL_MODE=#OLD_SQL_MODE;
SET FOREIGN_KEY_CHECKS=#OLD_FOREIGN_KEY_CHECKS;
SET UNIQUE_CHECKS=#OLD_UNIQUE_CHECKS;
-- MySQL Script generated by MySQL Workbench
-- 02/16/17 16:00:37
-- Model: New Model Version: 1.0
SET #OLD_UNIQUE_CHECKS=##UNIQUE_CHECKS, UNIQUE_CHECKS=0;
SET #OLD_FOREIGN_KEY_CHECKS=##FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0;
SET #OLD_SQL_MODE=##SQL_MODE, SQL_MODE='TRADITIONAL,ALLOW_INVALID_DATES';
-- -----------------------------------------------------
-- Schema mydb
-- -----------------------------------------------------
CREATE SCHEMA IF NOT EXISTS `mydb` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci ;
USE `mydb` ;
-- -----------------------------------------------------
-- Table `mydb`.`people`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`people` (
`idpeople` INT NOT NULL AUTO_INCREMENT,
`name` VARCHAR(45) NOT NULL,
`age` INT NOT NULL,
PRIMARY KEY (`idpeople`))
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`houses`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`houses` (
`idhouses` INT NOT NULL AUTO_INCREMENT,
`people_idpeople` INT NOT NULL,
`address` VARCHAR(45) NOT NULL,
`square_feet` INT NOT NULL,
PRIMARY KEY (`idhouses`),
INDEX `fk_houses_people1_idx` (`people_idpeople` ASC),
CONSTRAINT `fk_houses_people1`
FOREIGN KEY (`people_idpeople`)
REFERENCES `mydb`.`people` (`idpeople`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`houseHoldItems`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`houseHoldItems` (
`idhouseHoldItems` INT NOT NULL AUTO_INCREMENT,
`houses_idhouses` INT NOT NULL,
`uniqueKey` INT NOT NULL,
`value` DECIMAL(6,2) NOT NULL,
`dateBought` DATETIME NOT NULL,
PRIMARY KEY (`idhouseHoldItems`),
INDEX `fk_houseHoldItems_houses1_idx` (`houses_idhouses` ASC),
UNIQUE INDEX `unique_key` (`houses_idhouses` ASC, `uniqueKey` ASC),
CONSTRAINT `fk_houseHoldItems_houses1`
FOREIGN KEY (`houses_idhouses`)
REFERENCES `mydb`.`houses` (`idhouses`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`waterBeds`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`waterBeds` (
`gallonsWaterSize` INT NOT NULL,
`houseHoldItems_idhouseHoldItems` INT NOT NULL,
PRIMARY KEY (`houseHoldItems_idhouseHoldItems`),
CONSTRAINT `fk_waterBeds_houseHoldItems1`
FOREIGN KEY (`houseHoldItems_idhouseHoldItems`)
REFERENCES `mydb`.`houseHoldItems` (`idhouseHoldItems`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`televisions`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`televisions` (
`screenSize` INT NOT NULL,
`brandName` VARCHAR(45) NOT NULL,
`houseHoldItems_idhouseHoldItems` INT NOT NULL,
PRIMARY KEY (`houseHoldItems_idhouseHoldItems`),
CONSTRAINT `fk_televisions_houseHoldItems1`
FOREIGN KEY (`houseHoldItems_idhouseHoldItems`)
REFERENCES `mydb`.`houseHoldItems` (`idhouseHoldItems`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`refrigerators`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`refrigerators` (
`icecubeCapacity` INT NOT NULL,
`color` VARCHAR(45) NOT NULL,
`houseHoldItems_idhouseHoldItems` INT NOT NULL,
PRIMARY KEY (`houseHoldItems_idhouseHoldItems`),
CONSTRAINT `fk_refrigerators_houseHoldItems1`
FOREIGN KEY (`houseHoldItems_idhouseHoldItems`)
REFERENCES `mydb`.`houseHoldItems` (`idhouseHoldItems`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
SET SQL_MODE=#OLD_SQL_MODE;
SET FOREIGN_KEY_CHECKS=#OLD_FOREIGN_KEY_CHECKS;
SET UNIQUE_CHECKS=#OLD_UNIQUE_CHECKS;

Answer 1

Prefixing column names with the tablename gets tedious and unnecessary.
EAV is a bad way to go, but it is better than having separate tables for refrigerators and televisions. Follow the tag I added. The bottom line: have columns for columns you need to manipulate in MySQL throw the rest into a single JSON column.
For "many:many" tables, see my tips.