PHP6第3章-＃1215-无法添加外键约束

Question

I try to learn from book Professional PHP6 and in chapter 3 I need to create tables:

CREATE TABLE `entity` (
    `entityid` SERIAL PRIMARY KEY NOT NULL,
    `name1` varchar(100) NOT NULL,
    `name2` varchar(100) NOT NULL,
    `type` char(1) NOT NULL
);

and

CREATE TABLE `entityaddress` (
    `addressid` SERIAL PRIMARY KEY NOT NULL,
    `entityid` int,
    `saddress1` varchar(255),
    `saddress2` varchar(255),
    `scity` varchar(255),
    `cstate` char(2),
    `spostalcode` varchar(10),
    `stype` varchar(50),
    CONSTRAINT `fk_entityaddress_entityid`
        FOREIGN KEY (`entityid`) REFERENCES `entity`(`entityid`)
);

result is error: #1215 - Cannot add foreign key constraint

I check in original code for that book and there is sql file, which give me same error. ...is there anything wrong, or is something with my db in xampp? I try to create only tables and then create relation in designers, but I got program error...

I set InnoDB engine.

Thanks for any suggestion.

Answer 1

The type of entityid has to be the same in both tables. SERIAL is an alias for BIGINT UNSIGNED NOT NULL AUTO_INCREMENT UNIQUE . So change

`entityid` int,

to

`entityid` BIGINT UNSIGNED NOT NULL,