Question

I’ve a two table: A and B.
A has a relation with B as 1:1.

When I execute “Create entity classes from database”, Netbeans produces two entity classes but A has an annotation:

@OneToMany
private List<B> bCollections;

But I set a 1:1 relation, why this happen?

SQL script:

-- -----------------------------------------------------
-- Table `mydb`.`A`
-- ----------------------------------------------------

CREATE  TABLE IF NOT EXISTS `mydb`.`A` (

  `idA` INT NOT NULL ,

  `value` VARCHAR(45) NULL ,

  PRIMARY KEY (`idA`) )

ENGINE = InnoDB;

-- -----------------------------------------------------
-- Table `mydb`.`B`
-- -----------------------------------------------------

CREATE  TABLE IF NOT EXISTS `mydb`.`B` (

  `idB` INT NOT NULL ,

  `values` VARCHAR(45) NULL ,

  `A_idA` INT NOT NULL ,

  PRIMARY KEY (`idB`) ,

  INDEX `fk_B_A` (`A_idA` ASC) ,

  CONSTRAINT `fk_B_A`

    FOREIGN KEY (`A_idA` )

    REFERENCES `mydb`.`A` (`idA` )

    ON DELETE NO ACTION

    ON UPDATE NO ACTION)

ENGINE = InnoDB;

Answer 1

maybe add constraint

UNIQUE (A_idA)