mysql cannot create table - error 1005

Question

I'm a student and I'm just trying out some basic mysql. However I keep getting the same error when it comes to the following piece of code.

Error Code: 1005. Can't create table 'mydatabase.orders' (errno: 150)

CREATE TABLE Customer
(
P_ID int(3) UNSIGNED NOT NULL,
LastName varchar(10) NOT NULL,
FirstName varchar(10) NOT NULL,
Address varchar(20) NOT NULL,
City varchar(10) NOT NULL
);


CREATE TABLE Orders
(
O_ID int(3) UNSIGNED NOT NULL,
OrderNo int NOT NULL,
P_ID int(3) UNSIGNED NOT NULL,
PRIMARY KEY (O_ID),
FOREIGN KEY(P_ID)REFERENCES Customer(P_ID)
);

Answer 1

This should work, there was no PRIMARY KEY on the Customer table.

EDIT deleted the ON DELETE CASCADE ON UPDATE CASCADE clause, maybe is not needed

CREATE TABLE Customer(
    P_ID int(3) UNSIGNED NOT NULL,
    LastName varchar(10) NOT NULL,
    FirstName varchar(10) NOT NULL,
    Address varchar(20) NOT NULL,
    City varchar(10) NOT NULL,
    PRIMARY KEY (`P_ID`)
);

CREATE TABLE Orders(
    O_ID int(3) UNSIGNED NOT NULL,
    OrderNo int(3) NOT NULL,
    P_ID int(3) UNSIGNED NOT NULL,
    PRIMARY KEY (O_ID),
    CONSTRAINT `P_ID` FOREIGN KEY(`P_ID`) REFERENCES `Customer` (`P_ID`)
);