mysql - ERROR 1215: Cannot add foreign key constraint when using ON DELETE SET NULL

Question

I'm trying to create the following tables in MySQL. The first one:

CREATE TABLE IF NOT EXISTS address(
  address_id INT NOT NULL AUTO_INCREMENT,
  address_region VARCHAR(10) NOT NULL,
  address_country VARCHAR(20) NOT NULL,
  address_city VARCHAR(30) NOT NULL,
  PRIMARY KEY(address_id))ENGINE = InnoDB;

I created it successfully,but when I try to create another table as following

CREATE TABLE IF NOT EXISTS spot(
  spot_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  spot_address INT(11) NOT NULL,
  spot_name VARCHAR(50) NOT NULL,
  spot_desc VARCHAR(500) DEFAULT ' ',
  spot_speadd VARCHAR(100) NOT NULL,
  spot_viewtime INT DEFAULT 0,
  FOREIGN KEY(spot_address)
  REFERENCES address(address_id)
  ON DELETE SET NULL
  ON UPDATE SET NULL);

I get an error:

ERROR 1215 (HY000): Cannot add foreign key constraint

Why is this create table statement failing?

Answer 1

You have NOT NULL constraint on spot_address in the spot table and then try to set it to NULL on delete or update in the parent table address.