I'm trying to create a database using MySQL and having difficulties with my code. I created the base table with one attribute that I plan on using as a foreign key in another table but an error message comes up saying I cannot create the table. I only want help with creating that table as I know how to insert data.
create database aerogames_table;
CREATE TABLE
O_DETAILS
(
B_Number INT NOT NULL,
B_Name VARCHAR(60) NOT NULL,
Order_ID INT NOT NULL,
Order_CName VARCHAR(50) NOT NULL
)
engine=innodb;
CREATE TABLE
P_DETAILS
(
PRO_ID INT NOT NULL PRIMARY KEY,
Order_ID INT NOT NULL,
CONSTRAINT fk_OrdID_this FOREIGN KEY (Order_ID) REFERENCES O_DETAILS(Order_ID),
PRO_Seller VARCHAR (50) NOT NULL,
PRO_Name VARCHAR (50) NOT NULL,
PRO_Year INT NOT NULL,
PRO_Price INT NOT NULL
)
engine=innodb;
1005 - Can't create table 'aerogames_table.p_details' (errno: 150)
Due to this https://dev.mysql.com/doc/refman/5.6/en/create-table-foreign-keys.html
[CONSTRAINT [symbol]]
FOREIGN KEY [index_name] (index_col_name, ...)
REFERENCES tbl_name (index_col_name,...)
Foreign key need to reference to index column (no need to be primary key) so you need to create index on O_DETAILS.Order_ID like this
CREATE TABLE
O_DETAILS
(
B_Number INT NOT NULL,
B_Name VARCHAR(60) NOT NULL,
Order_ID INT NOT NULL,
Order_CName VARCHAR(50) NOT NULL,
KEY (Order_ID)
)
engine=innodb;
CREATE TABLE
P_DETAILS
(
PRO_ID INT NOT NULL PRIMARY KEY,
Order_ID INT NOT NULL,
CONSTRAINT fk_OrdID_this FOREIGN KEY (Order_ID) REFERENCES O_DETAILS(Order_ID),
PRO_Seller VARCHAR (50) NOT NULL,
PRO_Name VARCHAR (50) NOT NULL,
PRO_Year INT NOT NULL,
PRO_Price INT NOT NULL
)
engine=innodb;
Certainly if you make O_DETAILS.Order_ID to be primary key, it will also create for you and this works
Related
Somehow I can't create a join table for two entities I already have.
Here is what I run on MySQL just fine, the last one is the one I'm struggling with.
create table instructor_detail_table(
instructor_detail_id int not null primary key auto_increment,
instructor_class varchar(40) not null
);
create table instructor_table(
instructor_id int not null primary key auto_increment,
instructor_name varchar(40) not null,
instructor_detail_id int not null,
foreign key (instructor_detail_id) references instructor_detail_table (instructor_detail_id)
);
create table course_table(
course_id int not null primary key auto_increment,
course_class varchar(40) not null,
instructor_id int not null,
foreign key (instructor_id) references instructor_table (instructor_id)
);
create table student_table(
student_id int not null primary key auto_increment,
student_name varchar(40) not null,
student_age int not null
);
create table student_course_table(
student_id int not null,
course_id int not null,
foreign key (student_id) references student_table (student_id),
foreign key (course_id) references course_table (course_id),
primary key (student_id, course_id)
);
When I try to create the student_course_table MySQL complaints it can't open the referenced table student_table
Thanks in advance
You can have this problem if the storage engine is not the good one.
For example 'MyISAM' instead of 'InnoDB' for the table 'student_table'.
Because MyISAM doesn't support foreign key.
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'm using MySQL workbench and I am trying to create a table consist of foreign key using SQL Query. I am having problem with the Foreign part.
create table employee_position
(
ePID int primary key,
ePName varchar(45) not null,
eID int foreign key references employee_profile(eID)
)
Your syntax is wrong. Try:
create table employee_position
(
ePID int primary key,
ePName varchar(45) not null,
eID int,
foreign key (keyname) references employee_profile(eID)
)
For more information see the mysql documentation
create table employee_position
(
ePID int primary key,
ePName varchar(45) not null,
eID int,
foreign key (eID) references employee_profile(eID)
)
SQLFiddle demo
Check FOREIGN KEYS in MySQL.
Try this:
CREATE TABLE employee_position
(
ePID INT NOT NULL AUTO_INCREMENT,
ePName VARCHAR(45) NOT NULL,
eID INT NOT NULL,
PRIMARY KEY (ePID),
KEY CustomerID (eID),
CONSTRAINT FK_employee_position_EP
FOREIGN KEY (eID)
REFERENCES employee_profile (eID) ON DELETE CASCADE ON UPDATE CASCADE
);
There always be the error:"Cannot add foreign key constraint" when I create my last table.
System: Mac OS X 10.9
DB : MySQL 5.6.14
DBM : Sequel Pro
CREATE TABLE users (
uid INT AUTO_INCREMENT PRIMARY KEY,
uname VARCHAR(20) NOT NULL,
uemail VARCHAR(20) NOT NULL,
ucity VARCHAR(20),
upassw VARCHAR(20) NOT NULL
);
CREATE TABLE songs(
sid INT AUTO_INCREMENT PRIMARY KEY,
sname VARCHAR(20) NOT NULL,
srldate DATE NOT NULL
);
CREATE TABLE albums (
albid INT AUTO_INCREMENT PRIMARY KEY,
albname VARCHAR(20) NOT NULL,
albrldate DATE NOT NULL,
albrltime TIME NOT NULL
);
CREATE TABLE artists (
aid INT AUTO_INCREMENT PRIMARY KEY,
aname VARCHAR(20) NOT NULL
);
CREATE TABLE genres (
gid INT AUTO_INCREMENT PRIMARY KEY,
gname VARCHAR(20) NOT NULL
);
CREATE TABLE playlists (
uid INT NOT NULL,
sid INT NOT NULL,
plname VARCHAR(20) NOT NULL,
plmdate DATE NOT NULL,
plmtime TIME NOT NULL,
PRIMARY KEY(uid, sid, plname, plmdate, plmtime),
FOREIGN KEY(uid) REFERENCES users(uid),
FOREIGN KEY(sid) REFERENCES songs(sid)
);
CREATE TABLE u_like_a (
aid INT NOT NULL,
uid INT NOT NULL,
PRIMARY KEY(aid, uid),
FOREIGN KEY(aid) REFERENCES artists(aid),
FOREIGN KEY(uid) REFERENCES users(uid)
);
CREATE TABLE be_fan (
aid INT NOT NULL,
uid INT NOT NULL,
PRIMARY KEY(aid, uid),
FOREIGN KEY(aid) REFERENCES artists(aid),
FOREIGN KEY(uid) REFERENCES users(uid)
);
CREATE TABLE follow (
uid INT NOT NULL,
to_uid INT NOT NULL,
PRIMARY KEY(uid, to_uid),
FOREIGN KEY(uid) REFERENCES users(uid),
FOREIGN KEY(to_uid) REFERENCES users(uid)
);
CREATE TABLE u_like_g (
gid INT NOT NULL,
uid INT NOT NULL,
PRIMARY KEY(gid, uid),
FOREIGN KEY(gid) REFERENCES genres(gid),
FOREIGN KEY(uid) REFERENCES users(uid)
);
CREATE TABLE u_share_pl(
uid INT NOT NULL,
from_uid INT NOT NULL,
plname VARCHAR(20) NOT NULL,
plmdate DATE NOT NULL,
plmtime TIME NOT NULL,
PRIMARY KEY(uid, from_uid, plname, plmdate, plmtime),
FOREIGN KEY(uid) REFERENCES users(uid),
FOREIGN KEY(from_uid) REFERENCES users(uid),
FOREIGN KEY(plname) REFERENCES playlists(plname),
FOREIGN KEY(plmdate) REFERENCES playlists(plmdate),
FOREIGN KEY(plmtime) REFERENCES playlists(plmtime)
); #####---> This is the last table.
ERROR comes from here. I really don't why.
I have check the type for all attributes. The type and name of attributes have no problem.
But the mysql always say "Cannot add foreign key constraint"
Here is you reference wrong forgien REFERENCES users(from_uid) in last table.
FOREIGN KEY(from_uid) REFERENCES users(from_uid)
from_uid not belong to users
This should be
FOREIGN KEY(from_uid) REFERENCES users(uid)
your playLists table has primary key combination of four columns, so you should supply all these four columns as forieng key in u_share_pl table.
Another composite key as a reference should be a single constraint like
FOREIGN KEY(from_uid,sid,plname,plmdate,plmtime) REFERENCES playlists(uid,sid,plname,plmdate,plmtime)
Your last table Create should be:
CREATE TABLE u_share_pl(
uid INT NOT NULL,
from_uid INT NOT NULL,
sid INT NOT NULL,
plname VARCHAR(20) NOT NULL,
plmdate DATE NOT NULL,
plmtime TIME NOT NULL,
PRIMARY KEY(uid, from_uid, plname, plmdate, plmtime),
FOREIGN KEY(uid) REFERENCES users(uid),
FOREIGN KEY(from_uid,sid,plname,plmdate,plmtime) REFERENCES playlists(uid,sid,plname,plmdate,plmtime)
);
CREATE TABLE IF NOT EXISTS message(
id INT NOT NULL auto_increment,
userid INT NOT NULL,
date Date NOT NULL,
text varchar(255) NOT NULL,
PRIMARY KEY ('id')
FOREIGN KEY ('userid') REFERENCES users('id'));
I was just wondering if someone could help me in identifying a syntax error as I can not create a table.
Try to put , after the primary key declaration.
Update: I guess it should be
CREATE TABLE IF NOT EXISTS message (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
userid INT NOT NULL,
date Date NOT NULL,
text varchar(255) NOT NULL,
FOREIGN KEY (userid) REFERENCES users(id));
I'm assuming this is for MS SQL Server? If you get MS SQL Server Studio, you can script stuff which gives you an idea:
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[message]') AND type in (N'U'))
CREATE TABLE message(
id INT IDENTITY NOT NULL,
userid INT NOT NULL,
date Date NOT NULL,
text varchar(255) NOT NULL,
PRIMARY KEY (id),
FOREIGN KEY (userid) REFERENCES users(id))
GO
You query should be as below
CREATE TABLE IF NOT EXISTS message (
id INT auto_increment PRIMARY KEY,
userid INT NOT NULL,
date Date NOT NULL,
text varchar(255) NOT NULL,
FOREIGN KEY (userid) REFERENCES users(id));
Provided you have id as a primary key in users table.
CREATE TABLE users (id INT PRIMARY KEY)
Your query should look like this:
CREATE TABLE IF NOT EXISTS message(
id INT NOT NULL auto_increment,
userid INT NOT NULL,
date Date NOT NULL,
text varchar(255) NOT NULL,
PRIMARY KEY ('id'),
FOREIGN KEY ('userid') REFERENCES users('id')
) Engine=InnoDB;
Note the , after PRIMARY KEY ('id').
Small trick
You don't have to specify foreign keys in table definitions. It's practical when you do it like this (because dump may export tables in order that foreign keys will fail on creating/inserting):
CREATE TABLE 1; -- With references to table 2
CREATE TABLE 2;
INSERT INTO 1;
INSERT INTO 2;
ALTER TABLE 1 ADD FOREIGN KEY (user_id) REFERENCES 2 2(id);
Try to change the name of your table, May be message is an in-built keyword in MySQL.
Update to this: I guess it should be
CREATE TABLE IF NOT EXISTS myMessage (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
userid INT NOT NULL,
date Date NOT NULL,
text varchar(255) NOT NULL,
FOREIGN KEY (userid) REFERENCES users(id));