因此，当我想添加外键时出现错误。我在带有EER图模型的MySQL Workbench中添加了外键。工作台尝试添加的行是：

CREATE SCHEMA IF NOT EXISTS `barberDB` DEFAULT CHARACTER SET latin1 ;
USE `barberDB` ;

-- -----------------------------------------------------
-- Table `barberDB`.`BARBER`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `barberDB`.`BARBER` (
  `ID` INT NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(45) NULL,
  PRIMARY KEY (`ID`))
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `barberDB`.`CUSTOMER`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `barberDB`.`CUSTOMER` (
  `ID` INT NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(45) NULL,
  `isHaircut` INT NULL,
  `isBeard` INT NULL,
  `isEyebrows` INT NULL,
  `BARBER_ID` INT NOT NULL,
  PRIMARY KEY (`ID`),
  INDEX `fk_CUSTOMER_BARBER_idx` (`BARBER_ID` ASC) VISIBLE,
  CONSTRAINT `fk_CUSTOMER_BARBER`
    FOREIGN KEY (`BARBER_ID`)
    REFERENCES `barberDB`.`BARBER` (`ID`)
    ON DELETE CASCADE
    ON UPDATE CASCADE)
ENGINE = InnoDB;


SET SQL_MODE=@OLD_SQL_MODE;
SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS;
SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS;

我得到的错误是：

ERROR: Error 1064: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'VISIBLE,
  CONSTRAINT `fk_CUSTOMER_BARBER`
    FOREIGN KEY (`BARBER_ID`)
    REF' at line 12
SQL Code:
        -- -----------------------------------------------------
        -- Table `barberDB`.`CUSTOMER`
        -- -----------------------------------------------------
        CREATE TABLE IF NOT EXISTS `barberDB`.`CUSTOMER` (
          `ID` INT NOT NULL AUTO_INCREMENT,
          `name` VARCHAR(45) NULL,
          `isHaircut` INT NULL,
          `isBeard` INT NULL,
          `isEyebrows` INT NULL,
          `BARBER_ID` INT NOT NULL,
          PRIMARY KEY (`ID`),
          INDEX `fk_CUSTOMER_BARBER_idx` (`BARBER_ID` ASC) VISIBLE,
          CONSTRAINT `fk_CUSTOMER_BARBER`
            FOREIGN KEY (`BARBER_ID`)
            REFERENCES `barberDB`.`BARBER` (`ID`)
            ON DELETE CASCADE
            ON UPDATE CASCADE)
        ENGINE = InnoDB

SQL script execution finished: statements: 6 succeeded, 1 failed

Fetching back view definitions in final form.
Nothing to fetch

我搜索了解决方案，发现括号很重要或反引号，但是由于代码是由该工具创建的，因此对我来说似乎是正确的。是什么导致错误？