Creating a MySQL Table but get error - mysql

Question

I get
errnno 150: InnoDB Documentation
Supports transactions, row-level locking, and foreign keys
Here is the SQL:
-- Table structure for table `Serving_Info`
--
CREATE TABLE IF NOT EXISTS `Serving_Info` (
`id` int(255) NOT NULL AUTO_INCREMENT,
`Food_Value` varchar(40) NOT NULL,
`Food_name` varchar(40) NOT NULL,
`Served_On` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
`Oncall` varchar(128) NOT NULL,
Foreign key(`Oncall`) REFERENCES `employees`(`name`),
Foreign key(`Food_name`) REFERENCES `Foods`(`Food_name`),
PRIMARY KEY (`Oncall`,`Food_name`, `Served_On`)
);
Any idea what is causing the error? I have tried making id part of the primary key but that isn't solving the problem either.
Here are the statements for the tables I am referencing:
CREATE TABLE IF NOT EXISTS `employees` (
`id_user` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(128) NOT NULL,
`email` varchar(64) NOT NULL,
`phone_number` varchar(16) NOT NULL,
`username` varchar(16) NOT NULL,
`password` varchar(32) NOT NULL,
`confirmcode` varchar(32) DEFAULT NULL,
PRIMARY KEY (`id_user`)
);
--
-- Table structure for table `Foods`
--
CREATE TABLE IF NOT EXISTS `Foods` (
`Food_name` varchar(40) NOT NULL,
`CostPerRefill` double NOT NULL,
PRIMARY KEY (`Food_name`)
);
I just tried the below but I get the same error:
--
-- Table structure for table `Serving_Info`
--
CREATE TABLE IF NOT EXISTS `Serving_Info` (
`id` int(255) NOT NULL AUTO_INCREMENT,
`Food_Value` varchar(40) NOT NULL,
`Food_name` varchar(40) NOT NULL,
`Served_On` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
`Oncall` varchar(128),
Foreign key(`Oncall`) REFERENCES `employees`(`name`),
Foreign key(`Food_name`) REFERENCES `Foods`(`Food_name`),
PRIMARY KEY (`id`),
UNIQUE (`Oncall`,`Food_name`, `Served_On`)
);

Answer 1

Your problem is that the reference is to employees.name rather than employees.id_user. Try this:
CREATE TABLE IF NOT EXISTS `Serving_Info` (
`id` int(255) NOT NULL AUTO_INCREMENT,
`Food_Value` varchar(40) NOT NULL,
`Food_name` varchar(40) NOT NULL,
`Served_On` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
`Oncall` int,
PRIMARY KEY (`id`),
Foreign key(`Oncall`) REFERENCES `employees`(`id_user`),
Foreign key(`Food_name`) REFERENCES `Foods`(`Food_name`),
UNIQUE (`Oncall`,`Food_name`, `Served_On`)
);
Otherwise, change the employees table so name has an index:
CREATE TABLE IF NOT EXISTS `employees` (
`id_user` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(128) NOT NULL ,
`email` varchar(64) NOT NULL,
`phone_number` varchar(16) NOT NULL,
`username` varchar(16) NOT NULL,
`password` varchar(32) NOT NULL,
`confirmcode` varchar(32) DEFAULT NULL,
PRIMARY KEY (`id_user`),
KEY (name)
);
In practice, if you are going to use name this way, you should probably make that unique rather than just key.