MySQL Workbench "errno 150 foreign key" - mysql

Question

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';
CREATE SCHEMA IF NOT EXISTS `mydb` DEFAULT CHARACTER SET utf8 COLLATE
utf8_general_ci ;
USE `mydb` ;
-- -----------------------------------------------------
-- Table `mydb`.`Diploma`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`Diploma` (
`diploma_id` VARCHAR(5) NOT NULL,
`diploma_name` VARCHAR(90) NULL,
PRIMARY KEY (`diploma_id`)
) ENGINE=InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`School`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`School` (
`school_id` INT(1) NOT NULL,
`school_name` VARCHAR(45) NULL,
PRIMARY KEY (`school_id`)
) ENGINE=InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`Student`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`Student` (
`student_number` INT(8) NOT NULL,
`student_id` INT(8) NULL,
`student_name` VARCHAR(45) NULL,
`student_password` VARCHAR(45) NULL,
`student_mobile` INT(8) NULL,
`student_email` VARCHAR(45) NULL,
`diploma_id` VARCHAR(5) NOT NULL,
`school_id` INT(1) NOT NULL,
PRIMARY KEY (`student_number`),
INDEX `fk_Student_Diploma1_idx` (`diploma_id` ASC),
INDEX `fk_Student_School1_idx` (`school_id` ASC),
CONSTRAINT `fk_Student_Diploma1` FOREIGN KEY (`diploma_id`)
REFERENCES `mydb`.`Diploma` (`diploma_id`)
ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_Student_School1` FOREIGN KEY (`school_id`)
REFERENCES `mydb`.`School` (`school_id`)
ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`OFN`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`OFN` (
`ofn_id` INT(8) NOT NULL,
`ofn_username` VARCHAR(45) NULL,
`ofn_password` VARCHAR(45) NULL,
`ofn_email` VARCHAR(45) NULL,
PRIMARY KEY (`ofn_id`)
) ENGINE=InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`Appointment`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`Appointment` (
`appointment_id` INT(8) NOT NULL,
`appointment_date` DATE NULL,
`appointment_time` TIME NULL,
`ofn_id` INT(8) NOT NULL,
PRIMARY KEY (`appointment_id`),
INDEX `fk_Appointment_OFN1_idx` (`ofn_id` ASC),
CONSTRAINT `fk_Appointment_OFN1` FOREIGN KEY (`ofn_id`)
REFERENCES `mydb`.`OFN` (`ofn_id`)
ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB;
-- -----------------------------------------------------
-- Table `mydb`.`Booking`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `mydb`.`Booking` (
`student_number` INT(8) NOT NULL,
`appointment_id` INT(8) NOT NULL,
`booking_date` DATE NULL,
`booking_time` TIME NULL,
PRIMARY KEY (`student_number` , `appointment_id`),
INDEX `fk_Student_has_Appointment_Appointment1_idx` (`appointment_id` ASC),
INDEX `fk_Student_has_Appointment_Student1_idx` (`student_number` ASC),
CONSTRAINT `fk_Student_has_Appointment_Student1` FOREIGN KEY
(`student_number`)
REFERENCES `mydb`.`Student` (`student_number`)
ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_Student_has_Appointment_Appointment1` FOREIGN KEY (`appointment_id`)
REFERENCES `mydb`.`Appointment` (`appointment_id`)
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;
This is the code i was building but it gave an error
Error Code: 1005: Can't create table 'mydb'.'booking'
I tried looking through some of the previous question by people encountering the same problem but i am still stuck at this point.
Any help will be greatly appreciated, thank you.

Answer 1

Somehow it's the foreign key student_number.
I am thinking in these possibilities:
The foreign key name is a duplicate of an already existing key. Check that the name of your foreign key is unique within your database. Just add a few random characters to the end of your key name to test for this.
One or both of your tables is a MyISAM table. In order to use foreign keys, the tables must both be InnoDB. (Actually, if both tables are MyISAM then you won’t get an error message - it just won’t create the key.) In Query Browser, you can specify the table type.
One of the key field that you are trying to reference does not have an index and/or is not a primary key. If one of the fields in the relationship is not a primary key, you must create an index for that field.
Also check:
SET FOREIGN_KEY_CHECKS=0;