ERROR 1215: Cannot add foreign key constraint when using ON DELETE SET NULL
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?
您在spot表中的spot_address上有NOT NULL约束，然后尝试在删除或更新父表address将其设置为NULL 。
你可以试试这个：
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;
CREATE TABLE IF NOT EXISTS `spot`
(
`spot_id` INT(11) NOT NULL AUTO_INCREMENT,
`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(11) DEFAULT '0',
PRIMARY KEY (`spot_id`),
KEY `spot_address` (`spot_address`),
CONSTRAINT `spot_ibfk_1` FOREIGN KEY (`spot_address`) REFERENCES `address` (`address_id`)
) ENGINE=INNODB DEFAULT CHARSET=utf8
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