why the foreign key gives my headache?
first i created database names colorcode then paper table which works fine:
CREATE TABLE paper (
paper_id int(20) NOT NULL,
description VARCHAR(40) NOT NULL,
paper_color VARCHAR(40) NOT NULL,
PRIMARY KEY (paper_id, paper_color)
) ENGINE=InnoDB;
then brick table
CREATE TABLE brick(
brick_id int(20) NOT NULL,
description varchar(40) NOT NULL,
brick_color varchar (40) NOT NULL,
PRIMARY KEY (brick_id),
FOREIGN KEY (brick_color) REFERENCES paper(paper_color)
) ENGINE=InnoDB;
which doesn't=>
#1005 - Can't create table 'colorcode.brick' (errno: 150)
thank you for your help
create table paper (
paper_id int(20) not null,
description VARCHAR(40)not null,
paper_color VARCHAR(40) NOT NULL,
primary key (paper_id, paper_color),
INDEX(`paper_color`)
)engine=InnoDB;
create table brick (
brick_id int(20) not null,
description varchar(40) not null,
brick_color varchar (40) not null,
primary key (brick_id),
CONSTRAINT foreign key (`brick_color`) REFERENCES paper(`paper_color`)
)engine=InnoDB;
Demo: http://sqlfiddle.com/#!2/316d9
InnoDB permits a foreign key to reference any index column or group of
columns. However, in the referenced table, there must be an index
where the referenced columns are listed as the first columns in the
same order.
http://dev.mysql.com/doc/refman/5.6/en/innodb-foreign-key-constraints.html
"paper_color" has to be an index in order to reference.
Hope this helps.
Create a separate key for paper_color and it will work:
CREATE TABLE paper (
paper_id int(20) not null,
description VARCHAR(40)not null,
paper_color VARCHAR(40) NOT NULL,
PRIMARY KEY (paper_id, paper_color),
KEY (paper_color)
) ENGINE=InnoDB;
From SQL FOREIGN KEY Constraint
A FOREIGN KEY in one table points to a PRIMARY KEY in another table.
Now from your script, the PRIMARY KEY on table paper consists of columns paper_id, paper_color, but the foreign key referenceing it, only references paper(paper_color)
This techinically allows you to have 2 entries with
paper_id paper_color
1 blue
2 blue
which would satisfy the primary key constraint of table paper, but not the foreign key constraint on table brick
Changing the primary key on table paper to only paper_color would work though.
create table paper (
paper_id int(20) not null,
description VARCHAR(40)not null,
paper_color VARCHAR(40) NOT NULL,
primary key ( paper_color)
)engine=InnoDB;
create table brick(
brick_id int(20) not null,
description varchar(40) not null,
brick_color varchar (40) not null,
primary key (brick_id),
foreign key (brick_color) references paper(paper_color)
)engine=InnoDB
SQL Fiddle DEMO
Related
I am trying to create a child table that constraints 3 foreign keys from the parent but I receive an error 1215: cannot add foreign key constraint
parent table:
CREATE TABLE `Availability` (
`time_of_day` varchar(20) NOT NULL,
`day_of_week` varchar(20) NOT NULL,
`email` varchar(60) NOT NULL,
PRIMARY KEY (`time_of_day`,`day_of_week`,`email`),
KEY `email` (`email`),
CONSTRAINT `Availability_ibfk_1` FOREIGN KEY (`email`) REFERENCES `service_provider` (`email_service_provider`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
child table (which I cant build due to error mentioned above):
CREATE TABLE TEST1
(
num_request INT NOT NULL,
time_of_day VARCHAR(20) NOT NULL,
day_of_week VARCHAR(20) NOT NULL,
email VARCHAR(60) NOT NULL,
PRIMARY KEY (num_request),
Foreign key (time_of_day) references Availability(time_of_day),
Foreign key (day_of_week) references Availability(day_of_week),
Foreign key (email) references Availability(email)
);
Please show me what I'm doing wrong... Thank you all.
When you're making a foreign key to a table with a composite primary key (i.e. a key of multiple columns), you should make the foreign key composite as well.
CREATE TABLE TEST1
(
num_request INT NOT NULL,
time_of_day VARCHAR(20) NOT NULL,
day_of_week VARCHAR(20) NOT NULL,
email VARCHAR(60) NOT NULL,
PRIMARY KEY (num_request),
Foreign key (time_of_day, day_of_week, email) references Availability(time_of_day, day_of_week, email)
)
The columns of the foreign key should match the columns of the primary or unique key they reference. They should have the same number of columns, in the same order.
What you tried to do was create three separate constraints of one column each.
This question already has answers here:
MySQL Creating tables with Foreign Keys giving errno: 150
(20 answers)
Closed 1 year ago.
create table item
(
isbn varchar(25) not null,
title varchar(150) not null,
publisher_name varchar(50) not null,
classification_code varchar(10) not null,
format_type char(2),
constraint item_pk primary key(isbn)
);
create table copy
(
isbn varchar(25) not null,
copy_id int not null,
acquired_date not null,
constraint copy_pk primary key(isbn, copy_id),
constraint copy_fk foreign key(isbn) references item(isbn)
);
create table borrow (
isbn varchar(25) not null,
copy_id int not null,
user_id varchar(25) not null,
borrowed_datetime datetime not null,
returned_datetime datetime not null,
constraint borrow_pk primary key (isbn, copy_id, user_id, borrowed_datetime),
constraint borrow_fk_1 foreign key(isbn) references copy(isbn),
constraint borrow_fk_2 foreign key(copy_id) references copy(copy_id),
);
So this is my code here from MySQL and every time I try to run it, only Tables item and copy is created. Table borrow is not created due to "Error Code: 1822. Failed to add the foreign key constraint. Missing index for constraint 'borrow_fk_2' in the referenced table 'copy'".
My search engine is InnoDB.
To reference a compound primary key, you must declare a foreign key with the same number of columns as the primary key, and in the same order. In your case, you need the foreign key to be (isbn, copy_id) like this:
create table borrow (
isbn varchar(25) not null,
copy_id int not null,
user_id varchar(25) not null,
borrowed_datetime datetime not null,
returned_datetime datetime not null,
constraint borrow_pk primary key (isbn, copy_id, user_id, borrowed_datetime),
constraint borrow_fk_1 foreign key(isbn, copy_id) references copy(isbn, copy_id)
);
so pretty new to SQL I created 2 tables which I wanted to be related to one another but I'm getting an error "#1215 - Cannot add foreign key constraint" can someone point me to the right direction of this problem?
CREATE TABLE movie(
id INT(1) NOT NULL AUTO_INCREMENT,
nearname VARCHAR(25) NOT NULL,
release_date DATE NOT NULL,
lang VARCHAR(10) NOT NULL,
PRIMARY KEY(id),
CONSTRAINT same_movie FOREIGN KEY(id) REFERENCES movie_cast(movie_id)
);
CREATE TABLE movie_cast(
movie_id INT(1) NOT NULL AUTO_INCREMENT,
director_name VARCHAR(20) NOT NULL,
actor_name VARCHAR(20) NOT NULL,
actress_name VARCHAR(20) NOT NULL,
PRIMARY KEY(movie_id),
CONSTRAINT same_movie FOREIGN KEY(movie_id) REFERENCES movie(id)
);
You need to refer to the same column name as the primary key. In this case, it is called id:
CONSTRAINT same_movie FOREIGN KEY(movie_id) REFERENCES movie_cast(id)
Of course, your DDL doesn't define movie_cast. So, I am guessing the second table should be something like:
CREATE TABLE movie_cast (
id INT NOT NULL AUTO_INCREMENT,
movie_id int not null,
cast_name varchar(255)
PRIMARY KEY(id),
CONSTRAINT fk_movie_cast_movie FOREIGN KEY(movie_id) REFERENCES movie(movie_id)
);
I am working on a homework assignment. I have to build a database for a video store. All of the following works:
CREATE TABLE Stock
(
PKStock_ID VARCHAR(8) NOT NULL,
FKTitle VARCHAR(8) NOT NULL,
NoOfDVD INT(10) NOT NULL,
NoOfVHS INT(10) NOT NULL,
PRIMARY KEY (PKStock_ID)
);
CREATE TABLE Inventory
(
PKUnique_ID VARCHAR(8) NOT NULL,
DistributorSerialNo VARCHAR(8) NOT NULL,
Distributor_ID VARCHAR(8) NOT NULL,
FKTitle_ID VARCHAR(8) NOT NULL,
InStock CHAR(1) NOT NULL,
DateOut TIMESTAMP,
DateBack TIMESTAMP,
Customer_ID VARCHAR(8) NOT NULL,
Rental_Price DECIMAL(4,2) NOT NULL,
PRIMARY KEY (PKUnique_ID)
);
CREATE TABLE Movie
(
PKTitle_ID VARCHAR(8) NOT NULL,
FKTitle_ID VARCHAR(8) NOT NULL,
Title VARCHAR(30),
Genre VARCHAR(8),
YearReleased INT,
Length INT,
PRIMARY KEY (PKTitle_ID)
);
CREATE TABLE Actors
(
PKActor_ID VARCHAR(8) NOT NULL,
FKActor_ID VARCHAR(8) NOT NULL,
Actors VARCHAR(30),
PRIMARY KEY (PKActor_ID)
);
CREATE TABLE Awards
(
PKAward_ID VARCHAR(8) NOT NULL,
FKAward_ID VARCHAR(8) NOT NULL,
Awards VARCHAR(30),
PRIMARY KEY (PKAward_ID)
);
CREATE TABLE Directors
(
PKDirector_ID VARCHAR(8) NOT NULL,
FKDirector_ID VARCHAR(8) NOT NULL,
Directors VARCHAR(30),
PRIMARY KEY (PKDirector_ID)
);
CREATE TABLE ElectronicCatalogue
(
PKElectronicCatalogue VARCHAR(8) NOT NULL,
FKDistributor_ID VARCHAR(8) NOT NULL,
DistributorSerialNo VARCHAR(8) NOT NULL,
Price DECIMAL(6,2) NOT NULL,
PRIMARY KEY (PKElectronicCatalogue)
);
CREATE TABLE Distributors
(
PKDistributor_ID VARCHAR(8) NOT NULL,
FKDistributor_ID VARCHAR(8) NOT NULL,
NameOfDistributer VARCHAR(30) NOT NULL,
Horror CHAR(1) NOT NULL,
Drama CHAR(1) NOT NULL,
Comedy CHAR(1) NOT NULL,
Action CHAR(1) NOT NULL,
Thrillers CHAR(1) NOT NULL,
PRIMARY KEY (PKDistributor_ID)
);
CREATE TABLE Customers
(
PKCustomer_ID VARCHAR(8) NOT NULL,
FKUnique_ID VARCHAR(8) NOT NULL,
Name VARCHAR(30),
Address VARCHAR(100),
Phone INT NOT NULL,
PRIMARY KEY (PKCustomer_ID)
);
CREATE TABLE Fees
(
PKFee_ID VARCHAR(8) NOT NULL,
FK_ID VARCHAR(8) NOT NULL,
Damages DECIMAL(10,2) NOT NULL,
Late DECIMAL(10,2) NOT NULL,
PRIMARY KEY (PKFee_ID)
);
ALTER TABLE Stock
ADD FOREIGN KEY (FKTitle)
REFERENCES Inventory(PKUnique_ID);
ALTER TABLE Movie
ADD FOREIGN KEY (FKTitle_ID)
REFERENCES Stock (PKStock_ID);
ALTER TABLE Actors
ADD FOREIGN KEY (FKActor_ID)
REFERENCES Movie (PKTitle_ID);
ALTER TABLE Awards
ADD FOREIGN KEY (FKAward_ID)
REFERENCES Movie (PKTitle_ID);
ALTER TABLE Directors
ADD FOREIGN KEY (FKDirector_ID)
REFERENCES Movie (PKTitle_ID);
ALTER TABLE ElectronicCatalogue
ADD FOREIGN KEY (FKDistributor_ID)
REFERENCES Inventory (PKUnique_ID);
ALTER TABLE Distributors
ADD FOREIGN KEY (FKDistributor_ID)
REFERENCES ElectronicCatalogue (PKElectronicCatalogue);
I next want to connect the Inventory table to the customers table. When I do the following:
ALTER TABLE Customers
ADD FOREIGN KEY (FKUnique_ID)
REFERENCES Inventory (Customer_ID);
I get this error:
#1005 - Can't create table 'mm.#sql-9f69_110' (errno: 150)
What am I doing wrong?
Foreign key should point to a unique column (primary key or unique). Your Inventory (Customer_ID) is not unique.
I think you are trying to :
ALTER TABLE Inventory
ADD CONSTRAINT fk1_Inv FOREIGN KEY (Customer_ID)
REFERENCES Customers (PKCustomer_ID);
Not sure why you didn't get the full message but there's a command line tool bundled with MySQL that provides further information about cryptic error messages like this (or you can just Google for the error code):
C:>perror 150
MySQL error code 150: Foreign key constraint is incorrectly formed
If you have the SUPER privilege, you can get further details with this query:
show engine innodb status
And in this case you see this:
LATEST FOREIGN KEY ERROR
------------------------
130226 21:00:25 Error in foreign key constraint of table test/#sql-1d98_1:
FOREIGN KEY (FKUnique_ID)
REFERENCES Inventory (Customer_ID):
Cannot find an index in the referenced table where the
referenced columns appear as the first columns, or column types
in the table and the referenced table do not match for constraint.
Note that the internal storage type of ENUM and SET changed in
tables created with >= InnoDB-4.1.12, and such columns in old tables
cannot be referenced by such columns in new tables.
See http://dev.mysql.com/doc/refman/5.0/en/innodb-foreign-key-constraints.html
for correct foreign key definition.
So you are missing an index as explained.
Edit: As other answers point out, if there's no index it's because you're linking to the wrong column.
As Álvaro G. Vicario says you are missing an index, this is because you are not correctly using foreign keys.
ALTER TABLE Customers
ADD FOREIGN KEY (FKUnique_ID)
REFERENCES Inventory (Customer_ID);
This should be:
ALTER TABLE Inventory
ADD FOREIGN KEY (Customer_ID)
REFERENCES Customer(PKCustomer_ID);
The foreign key checks if the customer in the Inventory table actually exists in the Customers table. Thus Inventory here is the table you want to add the foreign key too and it references in primary key in the Customer table.
What you are trying to do is reference the Customer_ID in Inventory, which is just an VARCHAR(8)column and not an Primary Key (Index).
You should double check your other alter statements as well.
This turns out that you have different collation settings between these tables. In my case we had latin_swedish_ci and utf8_general_ci
I would like to ask something that troubles me many many days...
Here is what I mean:
I create these two tables:
CREATE TABLE IF NOT EXISTS journal (
issn varchar(20) NOT NULL,
j_title varchar(100) NOT NULL,
j_publisher varchar(30) NOT NULL,
PRIMARY KEY (issn)
) ENGINE=InnoDB;
CREATE TABLE IF NOT EXISTS volume (
volume_no int(11) NOT NULL,
issn varchar(20) NOT NULL,
year int(11) NOT NULL,
PRIMARY KEY (issn,volume_no),
FOREIGN KEY (issn) REFERENCES journal(issn)
) ENGINE=InnoDB;
When I try to create this:
CREATE TABLE IF NOT EXISTS issue (
issue_no int(11) NOT NULL,
issue_pages varchar(10) NOT NULL,
issue_date varchar(10) NOT NULL,
issn varchar(20) NOT NULL,
volume_no int(11) NOT NULL,
PRIMARY KEY (issue_no,issn,volume_no),
FOREIGN KEY (issn) REFERENCES journal(issn),
FOREIGN KEY (volume_no) REFERENCES volume(volume_no)
) ENGINE=InnoDB;
it throws an error (errno 150)
The error is in the foreign key volume_no.
Without FOREIGN KEY (volume_no) REFERENCES volume(volume_no)
the table is created without a problem.... I can't explain what's going on... I have seen it many times again and again but nothing!! Does anybody know what's going on?
Thanks in advance!!
I could see that the foreign key doesnt include issn but which is actually included in primary key for volumn table.
CREATE TABLE IF NOT EXISTS issue ( issue_no int(11) NOT NULL,
issue_pages varchar(10) NOT NULL,
issue_date varchar(10) NOT NULL,
issn varchar(20) NOT NULL,
volume_no int(11) NOT NULL,
PRIMARY KEY (issue_no,issn,volume_no),
FOREIGN KEY (issn,volume_no) REFERENCES volume(issn,volume_no) ) ENGINE=InnoDB;
Look at the below sql fiddle.
http://sqlfiddle.com/#!2/55a63
maybe volume_no needs to be UNSIGNED
FOREIGN keys must reference a PRIMARY or a UNIQUE key in the parent table.
You need only one Foreign Key at table issue, not two. And it should reference the Primary Key of volume:
CREATE TABLE IF NOT EXISTS issue (
issue_no int(11) NOT NULL,
issue_pages varchar(10) NOT NULL,
issue_date varchar(10) NOT NULL,
issn varchar(20) NOT NULL,
volume_no int(11) NOT NULL,
PRIMARY KEY (issn, volume_no, issue_no),
FOREIGN KEY (issn, volume_no)
REFERENCES volume(issn, volume_no)
) ENGINE=InnoDB;
If the PK of the parent table is more than one field, the order of the fields in the FK must be the same as the order in the PK.
issue: FOREIGN KEY (issn, volume_no) REFERENCES volume(issn, volume_no)
These conditions must be satisfied to not get error 150:
The two tables must be ENGINE=InnoDB.
The two tables must have the same charset.
The PK column(s) in the parent table and the FK column(s) must be the same data type.
The PK column(s) in the parent table and the FK column(s), if they have a define collation type, must have the same collation type;
If there is data already in the foreign key table, the FK column value(s) must match values in the parent table PK columns.
source: MySQL Creating tables with Foreign Keys giving errno: 150
I had about the same issue with my database. It wasn't about the definition of the foreign key, actually it was the definition of the primary key field.
CREATE TABLE tblProcesses (
fldProcessesID SMALLINT(5) UNIQUE NOT NULL AUTO_INCREMENT ,
CREATE TABLE tblProcessesMessage (
fldProcesses TEXT NOT NULL,
fldProcessesID VARCHAR(15) NOT NULL DEFAULT ,
The primary key in tblProcesses (fldProcessesID) did not have the UNSIGNED keyword while the foreign key in tblProcessesMessage (fldProcessesID) had the UNSIGNED keyword. This keyword was causing the problem - inconsistent type of field. So i added the UNSIGNED keyword to fldProcessesID in tblPreocesses:
CREATE TABLE tblProcesses (
fldProcessesID SMALLINT(5) UNSIGNED UNIQUE NOT NULL AUTO_INCREMENT,
I hope that this will help you solve your problems.
Best regards,
Nicholas