I have a SQL script that yields me the error:
DROP TABLE IF EXISTS test_db.users
;
CREATE TABLE users
(
id SERIAL,
username VARCHAR(20) NOT NULL,
password VARCHAR(20) NOT NULL,
PRIMARY KEY (id)
);
DROP TABLE IF EXISTS test_db.comments
;
CREATE TABLE comments
(
id SERIAL,
content varchar(255) NOT NULL,
userId BIGINT(20) NOT NULL,
CONSTRAINT fk_comments_has_user
FOREIGN KEY (userId)
REFERENCES test_db.users(id)
ON DELETE CASCADE,
PRIMARY KEY (id)
);
ERROR 1215 (HY000): Cannot add foreign key constraint
This error is not so specific, and I can't really seem to pinpoint the error by reading other posts regarding similar error.
The datatypes need to be the same bigint is not the same as serial.
Try this
drop table if exists comments;
DROP TABLE IF EXISTS temp;
CREATE TABLE temp
(
id bigint auto_increment,
username VARCHAR(20) NOT NULL,
password VARCHAR(20) NOT NULL,
PRIMARY KEY (id)
);
DROP TABLE IF EXISTS comments
;
CREATE TABLE comments
(
id bigint auto_increment,
content varchar(255) NOT NULL,
userId bigint NOT NULL,
CONSTRAINT fk_comments_has_user
FOREIGN KEY (userId)
REFERENCES temp(id)
ON DELETE CASCADE,
PRIMARY KEY (id)
);
Related
I'm trying to define some tables with SQL, but when I execute it I have an error. Below there is my code and the error which I receive.
CREATE TABLE Artists
(
id INT AUTO_INCREMENT PRIMARY KEY NOT NULL,
name VARCHAR(255) NOT NULL,
description VARCHAR(255)
);
CREATE TABLE Albums
(
id INT AUTO_INCREMENT PRIMARY KEY NOT NULL,
name VARCHAR(255) NOT NULL,
releasedate DATE,
artistid INT,
genreid INT,
picture VARCHAR(255),
CONSTRAINT `fk_albums_artists`
FOREIGN KEY (artistid) REFERENCES Artists(id),
CONSTRAINT `fk_albums_genres`
FOREIGN KEY (genreid) REFERENCES Genres(id)
);
CREATE TABLE Tracks
(
id INT(11) AUTO_INCREMENT PRIMARY KEY NOT NULL,
name VARCHAR(255) NOT NULL,
playtime INT NOT NULL,
albumid INT,
CONSTRAINT `fk_tracks_album`
FOREIGN KEY (albumid) REFERENCES Albums(id)
);
CREATE table Genres
(
id INT AUTO_INCREMENT PRIMARY KEY NOT NULL,
name VARCHAR(255) NOT NULL
);
Error in my SQL query:
MySQL said: Documentation
1005 - Can't create table musicplayer.Albums (errno: 150 "Foreign
key
constraint is incorrectly formed") (Details…)
Declare the tables in order, so the tables are defined before they are referenced:
CREATE TABLE Artists (
id int AUTO_INCREMENT PRIMARY KEY NOT null,
name varchar(255) not null,
description varchar(255)
);
CREATE table Genres(
id int AUTO_INCREMENT PRIMARY KEY NOT null,
name varchar(255) not null
);
CREATE TABLE Albums (
id int AUTO_INCREMENT PRIMARY KEY NOT null,
name varchar(255) not null,
releasedate date,
artistid int,
genreid int,
picture varchar(255),
CONSTRAINT `fk_albums_artists` FOREIGN KEY (artistid) REFERENCES Artists(id),
CONSTRAINT `fk_albums_genres` FOREIGN KEY (genreid) REFERENCES Genres(id)
);
CREATE TABLE Tracks(
id int(11) AUTO_INCREMENT PRIMARY KEY NOT null,
name varchar(255) not null,
playtime int not null,
albumid int,
CONSTRAINT `fk_tracks_album` FOREIGN KEY (albumid) REFERENCES Albums(id)
);
Here is a db<>fiddle.
You can still have tables that reference each other. However, you will need to declare such foreign key constraints using ALTER TABLE rather than in the CREATE TABLE statement. However, you do not need to do this for these table definitions.
I've created 3 tables using the query bellow. But when I try to drop the LOANACCOUNT table I receive an error:
Error:
Error Code: 1217. Cannot delete or update a parent row: a foreign key constraint fails
Create tables queries:
CREATE TABLE LOANACCOUNT
(
ID INT UNSIGNED NOT NULL AUTO_INCREMENT,
LOANACCOUNTTYPE VARCHAR(9) NOT NULL,
CREATIONDATE DATE NOT NULL,
CONSTRAINT LOAN_ACCOUNT_PK PRIMARY KEY (ID),
);
CREATE TABLE TRANSACTIONS
(
ID INT UNSIGNED NOT NULL AUTO_INCREMENT,
ACCOUNTID INT UNSIGNED NOT NULL,
TRANSACTIONTYPE VARCHAR(12) NOT NULL,
CONSTRAINT TRANSACTION_PK PRIMARY KEY (ID),
FOREIGN KEY LOANACCOUNT_FK (ACCOUNTID) REFERENCES LOANACCOUNT (ID) ON DELETE CASCADE
);
CREATE TABLE INSTALLMENT
(
ID INT UNSIGNED NOT NULL AUTO_INCREMENT,
ACCOUNTID INT UNSIGNED NOT NULL,
DUEDATE DATE NOT NULL,
CONSTRAINT INSTALLMENT_PK PRIMARY KEY (ID),
FOREIGN KEY LOANACCOUNT_FK (ACCOUNTID) REFERENCES LOANACCOUNT (ID) ON DELETE CASCADE
);
Drop table query:
DROP TABLE IF EXISTS LOANACCOUNT;
I know that there is something wrong with my foreign keys, but I don't know how to fix it.
As #Rigg Suggested need to drop other table before dropping LOANACCOUNT.
(i.e.) Parent table can't be drop unless there is no child linked.
For time being you can disable foreign key check and then drop those tables.
SET SESSION foreign_key_checks = 0;
DROP TABLE IF EXISTS LOANACCOUNT;
SET SESSION foreign_key_checks = 1;
I've created a table :
CREATE TABLE users (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY
,uName VARCHAR(50)
,uSecondName VARCHAR(50)
,eMail VARCHAR(50)
)
After this I even insert some data without any problems. But when I've tried to create new table with FOREIGN KEY referenced to users.id I've got an error:
CREATE TABLE posts(
id INT(6) AUTO_INCREMENT NOT NULL
,pTitle VARCHAR(155) NOT NULL DEFAULT 'not_set'
,pText TEXT
,pAuthor INT(6)
,PRIMARY KEY(id)
,CONSTRAINT fk_PerAuthor FOREIGN KEY (pAuthor)
REFERENCES users(id) ON DELETE CASCADE ON UPDATE CASCADE
);
Did I miss something?
Ok, maybe it's late and I'm being stupid, but I can't seem to figure out why I'm getting a Cannot add Foreign Key Constraint error for the following query
DROP TABLE IF EXISTS People_Lordships;
CREATE TABLE People_Lordships
(
Id INT PRIMARY KEY AUTO_INCREMENT,
PersonId INT NOT NULL,
LordshipId INT NOT NULL,
AssumedDate Date,
AbdicatedDate Date
);
DROP TABLE IF EXISTS People_Lordships_Current;
CREATE TABLE People_Lordships_Current
(
Id INT PRIMARY KEY AUTO_INCREMENT,
People_LordshipsId INT NOT NULL,
LordShipId INT NOT NULL,
CONSTRAINT Fk_People_Lordships_Current_People_LordshipsId_LordshipId
FOREIGN KEY (`LordshipId`,`People_LordshipsId`)
REFERENCES People_Lordships (`LordshipId`,`Id`)
ON DELETE RESTRICT ON UPDATE CASCADE,
CONSTRAINT UQ_People_Lordships_Current_LordshipId
UNIQUE KEY (`LordshipId`)
);
And yes, it is a database about noble titles... it's a long story
There is no column LordshipId in table People_Lordships.
Your foreign key definition attempts to reference a column that doesn't exist.
REFERENCES People_Lordships (`LordshipId`,`Id`)
^^^^^^^^^^^^
Figured this one out.
It turns out MySQL cannot add a foreign key constraint against a column that is not the first column in an index.
The following will work
DROP TABLE IF EXISTS People_Lordships;
CREATE TABLE People_Lordships
(
Id INT PRIMARY KEY AUTO_INCREMENT,
PersonId INT NOT NULL,
LordshipId INT NOT NULL,
AssumedDate Date,
AbdicatedDate Date,
INDEX Idx_LordshipId (LordshipId)
);
DROP TABLE IF EXISTS People_Lordships_Current;
CREATE TABLE People_Lordships_Current
(
Id INT PRIMARY KEY AUTO_INCREMENT,
People_LordshipsId INT NOT NULL,
LordShipId INT NOT NULL,
CONSTRAINT Fk_People_Lordships_Current_People_LordshipsId_LordshipId
FOREIGN KEY (`LordshipId`,`People_LordshipsId`)
REFERENCES People_Lordships (`LordshipId`,`Id`)
ON DELETE RESTRICT ON UPDATE CASCADE,
CONSTRAINT UQ_People_Lordships_Current_LordshipId
UNIQUE KEY (`LordshipId`)
);
I'm trying to find what causes error 1005 on creation of my tables:
CREATE TABLE hospitals(
hosp_id INT NOT NULL AUTO_INCREMENT,
hosp_name VARCHAR(100) NOT NULL,
hosp_address VARCHAR(100) NOT NULL,
hosp_ph_number VARCHAR(8) NOT NULL,
PRIMARY KEY(hosp_id)
) TYPE=InnoDB CHARACTER SET=UTF8;
CREATE TABLE transport(
tr_regnumber VARCHAR(8) NOT NULL,
tr_brand VARCHAR(15) NOT NULL,
tr_description VARCHAR(25),
hosp_id INT,
PRIMARY KEY (tr_regnumber),
FOREIGN KEY (hosp_id) REFERENCES hospitals(hosp_id)
) TYPE=InnoDB CHARACTER SET=UTF8;
CREATE TABLE buildings(
build_id INT NOT NULL AUTO_INCREMENT,
hosp_id INT,
build_address VARCHAR(100) NOT NULL,
build_description VARCHAR(25),
PRIMARY KEY (build_id),
FOREIGN KEY (hosp_id) REFERENCES hospitals(hosp_id)
) TYPE=InnoDB CHARACTER SET=UTF8;
CREATE TABLE patients(
pat_id INT NOT NULL AUTO_INCREMENT,
pat_fullname VARCHAR(150) NOT NULL,
diagnosis VARCHAR(150) NOT NULL,
emp_id INT,
pat_ph_number VARCHAR(8),
pat_address VARCHAR(100),
hosp_id INT,
pl_num INT,
PRIMARY KEY (pat_id),
FOREIGN KEY (pl_num) REFERENCES places(pl_number),
FOREIGN KEY (emp_id) REFERENCES employees(emp_id),
FOREIGN KEY (hosp_id) REFERENCES hospitals(hosp_id)
) TYPE=InnoDB CHARACTER SET=UTF8;
CREATE TABLE places(
pl_number INT NOT NULL AUTO_INCREMENT,
pat_id INT NOT NULL,
hosp_id INT NOT NULL,
PRIMARY KEY (pl_number),
FOREIGN KEY (pat_id) REFERENCES patients(pat_id),
FOREIGN KEY (hosp_id) REFERENCES hospitals(hosp_id)
) TYPE=InnoDB CHARACTER SET=UTF8;
CREATE TABLE employees(
emp_id INT NOT NULL AUTO_INCREMENT,
emp_fullname VARCHAR(150) NOT NULL,
emp_position VARCHAR(100) NOT NULL,
emp_ph_number VARCHAR(8),
emp_home_address VARCHAR(100),
hosp_id INT NOT NULL,
PRIMARY KEY (emp_id),
FOREIGN KEY (hosp_id) REFERENCES hospitals(hosp_id)
) TYPE=InnoDB CHARACTER SET=UTF8;
Here are errors:
ERROR 1005 (HY000): Can't create table 'hospital_db.patients' (errno: 150)
ERROR 1005 (HY000): Can't create table 'hospital_db.places' (errno: 150)
Here's output of SHOW INNODB STATUS:
------------------------
LATEST FOREIGN KEY ERROR
------------------------
110829 11:52:01 Error in foreign key constraint of table hospital_db/places:
FOREIGN KEY (pat_id) REFERENCES patients(pat_id),
FOREIGN KEY (hosp_id) REFERENCES hospitals(hosp_id)
) TYPE=InnoDB CHARACTER SET=UTF8:
Cannot resolve table name close to:
(pat_id),
FOREIGN KEY (hosp_id) REFERENCES hospitals(hosp_id)
) TYPE=InnoDB CHARACTER SET=UTF8
I use MySQL v5.1.49.
This seems to be to do with the order you're creating the tables and the foreign key dependencies you have.
Try disabling foreign key checks before creating the tables and enabling them after like so:
SET foreign_key_checks = 0;
-- Your create queries here
SET foreign_key_checks = 1;
Cheers
I know this one is solved, but for the Googlers out here, I did this in mysql workbench:
Primary keys have 'not null' checked by default. Creating a foreign key in a child table and also checking it as 'not null' will cause this error. It took me ages to find this myself because its an exception of what people suggest (making sure everything in the column is of the same type as the parent key). So just leave 'not null' unchecked on the foreign key
thought this might help saving people some time :)
You create FK on table 'places' before creating this table. Table places is created after table patients which try to use table which doesn't exist yet.
It seems that you have crossing foreign keys. In this case it's better to create tables without FKs and than use ALter TABLE for adding FKs.