Foreign Keys and MySQL Errors

Question

I have the following script to create a table in MySQL version 5.1 which is to refer to 3 other tables. All 3 tables have been created using InnoDB, and all 3 tables have the ID column defined as INT.

I have created other tables successfully which reference ACCOUNT and PERSON, however, this is the first table which references ADDRESS, so I've included the definition for that table, as run, below as well.

The error which I'm getting is ERROR 1005 (HY000) with errno 150, which I understand to be relating to foreign key creation.

The script which fails is (extra columns removed for simplicity):

CREATE TABLE WORK_ORDER (
    ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
    ACCOUNT_ID INT NOT NULL,
    CUSTOMER_ID INT NOT NULL,
    SALES_ID INT,
    TRADES_ID INT,
    LOCATION_ID INT NOT NULL,
    INDEX CUST_INDEX(CUSTOMER_ID),
    INDEX SALES_INDEX(SALES_ID),
    INDEX TRADES_INDEX(TRADES_ID),
    INDEX ACCOUNT_INDEX(ACCOUNT_ID),
    INDEX LOCATION_INDEX(LOCATION_ID),
    FOREIGN KEY (CUSTOMER_ID) REFERENCES PERSON(ID) ON DELETE CASCADE,
    FOREIGN KEY (SALES_ID) REFERENCES PERSON(ID) ON DELETE SET NULL,
    FOREIGN KEY (TRADES_ID) REFERENCES PERSON(ID) ON DELETE SET NULL,
    FOREIGN KEY (ACCOUNT_ID) REFERENCES ACCOUNT(ID) ON DELETE CASCADE,
    FOREIGN KEY (LOCATION_ID) REFERENCES ADDRESS(ID) ON DELETE SET NULL
) ENGINE=InnoDB;

The SQL statement used to create the ADDRESS table is below (extra columns removed for simplicity).

CREATE TABLE ADDRESS (
    ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
    PERSON_ID INT NOT NULL,
    ACCOUNT_ID INT NOT NULL,
    ADDRESS_L1 VARCHAR(50),
    ADDRESS_L2 VARCHAR(50),
    CITY VARCHAR(25),
    PROVINCE VARCHAR(20),
    POSTAL_CODE VARCHAR(6),
    COUNTRY VARCHAR(25),
    INDEX CUST_INDEX(PERSON_ID),
    INDEX ACCOUNT_INDEX(ACCOUNT_ID),
    FOREIGN KEY (ACCOUNT_ID) REFERENCES ACCOUNT(ID) ON DELETE CASCADE,
    FOREIGN KEY (PERSON_ID) REFERENCES PERSON(ID) ON DELETE CASCADE
) ENGINE=InnoDB;

I've browsed through several questions here dealing with similar issues, but most seem to be duplicate definitions and non-matching field types, as well as some not using InnoDB for one or the other of the tables. However, none of these seem to be the problem. Any ideas?

Answer 1

You can always issue a 'SHOW ENGINE INNODB STATUS' command. Buried in the output will be a "LATEST FOREIGN KEY ERROR" section, which will have more details on exactly what caused the '150' error:

mysql> create table a (x int not null) type=innodb;
Query OK, 0 rows affected, 1 warning (0.02 sec)

mysql> create table b (y int not null, foreign key (y) references a (x) on delete set null) type=innodb;
ERROR 1005 (HY000): Can't create table './test/b.frm' (errno: 150)

mysql> show engine innodb status;
[..... snip snip snip ...]
------------------------
LATEST FOREIGN KEY ERROR
------------------------
091129 16:32:41 Error in foreign key constraint of table test/b:
foreign key (y) references a (x) on delete set null) type=innodb:
You have defined a SET NULL condition though some of the
columns are defined as NOT NULL.
[.... snip snip snip ...]