is this in 3NF ?
create table movies(
id numeric primary key not null default autoincrement,
name varchar(50) not null,
release-date Date,
price numeric,
rating numeric,
length numeric,
description varchar(1500)
);
create table movies(
id numeric primary key,
name varchar(20)
);
create table genre(
name varchar(20) primary key
);
create table directors(
id numeric primary key not null default autoincrement,
first-name varchar(32) not null,
last-name varchar(32) not null,
gender varchar(8),
dob Date,
biography varchar(1000)
);
create table movie-Star(
id numeric primary key not null default autoincrement,
first-name varchar(20) not null,
last-name varchar(20) not null,
gender varchar(8),
dob Date,
hometown varchar(20)
);
create table movies-cast(
movie-id numeric references movies(id),
actor-id numeric references movie-Star(id),
role varchar(32),
primary key (movie-id, actor-id)
);
Create table Studio(
studio-id numeric references directors(id)
Directer-name varchar(20) not null
name varchar(20) primary key
);
create table directors(
id numeric primary key not null default autoincrement,
first-name varchar(32) not null,
last-name varchar(32) not null,
gender varchar(8),
dob Date,
biography varchar(1000)
);
It looks pretty well structured. I don't see any normalization problems. However:
Movies and Directors tables are created twice.
Genre table is not used for anything (presumably should be in movies).
Same with Studios.
Current arrangement allows only one director per studio. This should probably be A) one studio per director (add studio_id column to directors) or more likely B) many-to-many relationship between studio and director (add new studio_directors table).
Current arrangement does not associate Director with Movie.
You might consider combining Director and Movie-Start into one table called Talent. You have data duplication in which a star is also a director. This is the biggest normalization issue with your design.
if all can not be duplicated again then it is included 3NF.
make sure there are not duplicate data again
It has e PK, so it's in 1NF. It's PK is not composite, so it's in 2NF. All the columns are dependent on nothing but the key, so it's in 3NF. There no keys other than PK, so it's in BCNF.
Related
I have this table:
CREATE TABLE cars_info.cars
(
id SERIAL,
owner_id INTEGER,
brand VARCHAR(50) NOT NULL,
model VARCHAR(50) NOT NULL,
color VARCHAR(50) NOT NULL,
register_number VARCHAR(50) NOT NULL,
created DATE NOT NULL,
PRIMARY KEY(id, brand, model, color, register_number, created),
CONSTRAINT fk_owner_id
FOREIGN KEY(owner_id)
REFERENCES persons_info.persons(id)
);
But when I tried create another table like this:
CREATE TABLE cars_info.violations
(
id SERIAL PRIMARY KEY,
car_id INTEGER NOT NULL,
message VARCHAR(100) NOT NULL,
active BOOLEAN NOT NULL,
CONSTRAINT fk_car_id
FOREIGN KEY(car_id)
REFERENCES cars_info.cars(id)
);
I get an error about that
Target external table "cars" does not have a unique constraint corresponding to the given keys
How can I fix that? I'm a beginner in SQL and don't know how to go about googling that
Your primary key definition for cars
PRIMARY KEY(id, brand, model, color, register_number, created)
makes no sense: The id column, being serial, is itself unique and it alone should be the primary key.
Delete your primary key definition and change the id column definition to:
id serial not null primary key
Unrelated, but best practice is to name table in the singular; name your tables car and violation rather than cars and violations
I'm new to SQL and there are a lot of things going on that I still don't seem to quite understand. I have the following table
CREATE TABLE Person
(
First_Name varchar(20) NOT NULL,
Name varchar(20) NOT NULL,
Address varchar(50) NOT NULL,
PRIMARY KEY (First_Name, Name, Address)
);
I know want to create another table that has the primary key from the table Person as foreign key and also as primary key:
CREATE TABLE Purchase
(
No_Installments int,
Rate int,
Person varchar(50) NOT NULL PRIMARY KEY,
CONSTRAINT PFK
FOREIGN KEY (Person) REFERENCES Person (First_Name, Name, Address)
);
For some reason this doesn't work and I get an error every time. I've already looked up the other threads here on stackoverflow, but they don't really seem to help me. What am I doing wrong?
If you have a compound PK made up from three columns, then any child table that wants to establish a foreign key relationship must ALSO have all those 3 columns and use all 3 columns to establish the FK relationship.
FK-PK relationship is an all or nothing proposal - you cannot reference only parts of a primary key - either you reference all columns - or you don't reference.
CREATE TABLE Purchase
(
No_Installments int,
Rate int,
Person varchar(50) NOT NULL PRIMARY KEY,
First_Name varchar(20) NOT NULL,
Name varchar(20) NOT NULL,
Address varchar(50) NOT NULL,
CONSTRAINT PFK
FOREIGN KEY (First_Name, Name, Address)
REFERENCES Person (First_Name, Name, Address)
);
Have an integer primary key, using identity, auto_increment, serial or whatever for your database:
CREATE TABLE Person (
PersonId int identity PRIMARY KEY
First_Name varchar(20) NOT NULL,
Name varchar(20) NOT NULL,
Address varchar(50) NOT NULL,
CONSTRAINT unq_person_3 UNIQUE (First_Name, Name, Address)
);
Then use the identity column for the reference:
CREATE TABLE Purchase (
PurchaseId int identity PRIMARY KEY,
No_Installments int,
Rate int,
PersonId int,
CONSTRAINT PFK
FOREIGN KEY (PersonId) REFERENCES Person (PersonId)
);
Notes:
You really don't want to have to deal with a composite primary key. Have you thought about what the joins will look like?
You don't want a primary key where the values are subject to change. What happens when someone changes his/her name? When someone moves?
Person should not be the primary key in Purchases. Are you only allowing someone to make one purchase?
As noted initially, how you generate such a column varies by database; identity happens to be the way that SQL Server does this.
You probably want to assign a unique ID to each person, not relying on their name to be unique or for an address to be required. That ID will be your Primary key and foreign key. Your purchase table should also have its own id for its primary key -- otherwise because primary keys must be unique, each person can only have one purchase.
CREATE TABLE Person (
id serial NOT NULL,
First_Name varchar(20) NOT NULL,
Name varchar(20) NOT NULL,
Address varchar(50) NOT NULL,
PRIMARY KEY (id));
CREATE TABLE Purchase (
id serial NOT NULL,
No_Installments int,
Rate int,
Person int NOT NULL,
FOREIGN KEY (Person) REFERENCES Person (id),
PRIMARY KEY (id));
I'm trying to insert data into my SQL Server 2014 build and I keep getting this error. I tried searching all over the internet and at my whits end, I sort of get what people were saying but still having difficulty understanding what's wrong with my particular code.
All tables are empty without data. I cannot add data once the foreign keys are set. I read that both tables must be populated for this to work but how does that happen when I can't add anything? If I add data before the foreign key, then I'm unable to add foreign keys. Please help!
When trying to insert data into Gym row using the INSERT INTO I get this error:
The INSERT statement conflicted with the FOREIGN KEY constraint "FK__Gym__staffNo". The conflict occurred in database "FitnessApp", table "dbo.Staff", column 'staffNo'.
This also happens when trying to add data into the Equipment or Staff tables as well.
See code here:
Schema:
CREATE TABLE Gym
(
gymNo int NOT NULL IDENTITY(1,1),
staffNo int NOT NULL,
streetAddress varchar(100) NOT NULL,
streetAddress2 varchar(100) NULL,
city varchar(50) NOT NULL,
state char(2) NOT NULL,
zip char(5) NOT NULL,
phone char(10) NOT NULL
) ON [fitnessPlusGroup1];
CREATE TABLE Staff
(
staffNo int NOT NULL IDENTITY(1,1),
gymNo int NOT NULL,
position varchar(50) NOT NULL,
firstName varchar(50) NOT NULL,
lastName varchar(50) NOT NULL,
streetAddress varchar(100) NOT NULL,
streetAddress2 varchar(100) NULL,
city varchar(50) NOT NULL,
state char(2) NOT NULL,
zip char(5) NOT NULL,
phone char(10) NOT NULL,
hireDate date NOT NULL
) ON [fitnessPlusGroup1];
CREATE TABLE Member
(
memberNo int NOT NULL IDENTITY(1,1),
gymNo int NOT NULL,
firstName varchar(30) NOT NULL,
lastName varchar(30) NOT NULL,
streetAddress varchar(100) NOT NULL,
streetAddress2 varchar(100) NULL,
city varchar(50) NOT NULL,
state char(2) NOT NULL,
zip char(5) NOT NULL,
phone char(10) NOT NULL,
memberSince date NOT NULL,
scheduleID int NULL
) ON [fitnessPlusGroup1];
CREATE TABLE Schedule
(
scheduleID int NOT NULL IDENTITY(1,1),
staffNo int NOT NULL,
trainDate date NOT NULL,
trainTime time(0) NOT NULL
) ON [fitnessPlusGroup1];
CREATE TABLE Equipment
(
equipNo int NOT NULL IDENTITY(1,1),
gymNo int NOT NULL,
staffNo int NOT NULL,
name varchar(50) NOT NULL,
quantity int NOT NULL
) ON [fitnessPlusGroup1];
Foreign key relationships setup:
ALTER TABLE Gym
ADD FOREIGN KEY (staffNo) REFERENCES Staff(staffNo);
ALTER TABLE Staff
ADD FOREIGN KEY (gymNo) REFERENCES Gym(gymNo);
ALTER TABLE Member
ADD FOREIGN KEY (gymNo) REFERENCES Gym(gymNo);
ALTER TABLE Member
ADD FOREIGN KEY (scheduleID) REFERENCES Schedule(scheduleID);
ALTER TABLE Schedule
ADD FOREIGN KEY (staffNo) REFERENCES Staff(staffNo);
ALTER TABLE Equipment
ADD FOREIGN KEY (gymNo) REFERENCES Gym(gymNo);
ALTER TABLE Equipment
ADD FOREIGN KEY (staffNo) REFERENCES Staff(staffNo);
The insert commands that give errors:
INSERT INTO Gym(staffNo, streetAddress, streetAddress2, city, state, zip, phone)
VALUES (1, '7300 W Greens Rd', NULL, 'Houston', 'TX', '77064', '2818946151');
Any help would be much appreciated sorry if this seems like a bit much and I hope I provided all the info I could..
I think the problem is in your table design. Take these two FKEY, as an exmpale:
ALTER TABLE Gym
ADD FOREIGN KEY (staffNo) REFERENCES Staff(staffNo);
ALTER TABLE Staff
ADD FOREIGN KEY (gymNo) REFERENCES Gym(gymNo);
You cannot add a record to Gym until you've added the supporting staffNo to Staff. But you cannot add a record to Staff until you've added the supporting gymNo to Gym. These keys prevent you populating either table, as both require records to be present in the other.
Why is this? Because an FKey is like a promise. It guarantees that the value in column x can always be found in table y. In order to fulfill this promise table y must be populated first. But when you have a circular reference, back to the original table, this can never be achieved.
Here is one possible solution. You could remove the staffNo from Gym and GymNo from Staff. Then add a new table StaffGym. This table would have two fields staffNo and gymNo. It would be populated after Staff and Gym, providing a bridge between the two. This is called a cross reference table, or sometimes xref for short.
You say:
All tables are empty without data.
So there is no staffNo with id = 1 in your Staff. You've got a foreign key constraint so you can only reference items that exist. So you first need to populate the lookup data in Staff before you can link to it with an ID.
Also, remove one of the constraint between Staff and Gym, you have this:
ALTER TABLE Gym
ADD FOREIGN KEY (staffNo)
REFERENCES Staff(staffNo);
ALTER TABLE Staff
ADD FOREIGN KEY (gymNo)
REFERENCES Gym(gymNo);
When you only need one of these. I'd say remove it from Gym, as a Gym could have many staff I'd assume, and also remove the StaffNo column from Gym. As this is preventing you from creating one without the other. Once you've removed that link, you should insert data in the correct order.
The order of the inserts is key. If you remove the column I suggested above, you should insert in the following order based on your constraints:
Gym
Staff (requires gym record)
Schedule (requires staff record)
Member (requires schedule record)
Equipment (requires gym and staff record)
I'm in a bit of a mix right now, I have a Table called Avatars, which has a foreign key called Family. Now, in the family table, I have two Foreign Keys called Mother and Father - Now this is the confusing bit, in both the Mother and Father Tables, there is a Foreign key called Avatar_ID which is of course the Primary Key to the Avatars table. I'm not sure if that's even allowed in SQL PLUS.
Whenever I try and enter the tables 'Family, Mother or Father', I keep getting the error:ORA-02291: integrity constraint (SG304.FK_FATHER_ID) violated - parent key not found.
Is there any way around this? Or will I have to change my code completely? A sample of the code is below.
CREATE TABLE Avatars (
Avatar_ID VARCHAR(10) NOT NULL,
Avatar_Name VARCHAR(30),
AvA_DOB DATE,
Age VARCHAR(30),
Gender VARCHAR(30),
Strength_Indicated INT,
Hoard INT,
Avatar_Level VARCHAR(30),
Skill VARCHAR(30),
Original_Owner VARCHAR(30),
Family_ID VARCHAR(10) NOT NULL,
Species_ID VARCHAR(10) NOT NULL,
Inventory_ID VARCHAR(30) NOT NULL,
Weapon_ID VARCHAR(10),
Player_ID VARCHAR(10) NOT NULL,
PRIMARY KEY (Avatar_ID));
CREATE TABLE Family (
Family_ID VARCHAR(10) NOT NULL,
Mother_ID VARCHAR(10) NOT NULL,
Father_ID VARCHAR(10) NOT NULL,
primary key(Family_ID)
);
CREATE TABLE Mother (
Mother_ID VARCHAR(10) NOT NULL,
Avatar_ID VARCHAR(10) NOT NULL,
primary key(Mother_ID)
);
CREATE TABLE Father (
Father_ID VARCHAR(10) NOT NULL,
Avatar_ID VARCHAR(10) NOT NULL,
primary key(Father_ID)
);
ALTER TABLE Avatars
ADD CONSTRAINT fk_Family_ID
FOREIGN KEY (Family_ID)
REFERENCES Family(Family_ID);
ALTER TABLE Family
ADD CONSTRAINT fk_Mother_ID
FOREIGN KEY (Mother_ID)
REFERENCES Mother(Mother_ID);
ALTER TABLE Family
ADD CONSTRAINT fk_Father_ID
FOREIGN KEY (Father_ID)
REFERENCES Father(Father_ID);
ALTER TABLE Father
ADD CONSTRAINT fk_Avatar_ID
FOREIGN KEY (Avatar_ID)
REFERENCES Avatars(Avatar_ID);
ALTER TABLE Mother
ADD CONSTRAINT fk_Avatars_ID
FOREIGN KEY (Avatar_ID)
REFERENCES Avatars(Avatar_ID);
INSERT INTO Avatars (Avatar_ID,Avatar_Name,AvA_DOB,Age,Gender,Strength_Indicated,Hoard,Avatar_Level, Skill, Original_Owner, Family_ID,Species_ID,Inventory_ID,Player_ID) VALUES
('Ava01','Verda','20-JAN-2014','1 year 2 months','Female','100','20','Master','Leader',' - ',' - ','DRA1','MasterInventory','Player07');
Thanks in advance for any help given! (:
Foreign key refers to a record in parent table. In your INSERT statement you are inserting value ' - ' into a column parent_id. In this error message oracle informs you that there is no record with value ' - ' in a column family_id of a table family. As I can understand, you are trying to use ' - ' as 'absence of value'. There is special value for that - NULL. So you need to write your statement as:
INSERT INTO Avatars (Avatar_ID, Avatar_Name, AvA_DOB,
Age, Gender, Strength_Indicated, Hoard, Avatar_Level, Skill,
Original_Owner, Family_ID, Species_ID, Inventory_ID, Player_ID)
VALUES ('Ava01', 'Verda', '20-JAN-2014', '1 year 2 months' ,'Female',
'100', '20', 'Master', 'Leader', NULL, NULL, 'DRA1',
'MasterInventory', 'Player07');
Also I can recommend some changes to your schema. First of all, use number data type for primary keys - it allows you to use sequences to generate unique values. Also, I don't know details of the problem, but "family relations" in your tables look a bit complicated. You can describe it in a single table:
create table family_tree (
person_id number primary key,
father_id number,
mother_id number,
sex char(1),
name varchar2(50),
family_name varchar2(50));
add constraint fk_mother_id foreign key (mother_id)
references family_tree (person_id);
add constraint fk_father_id foreign key (father_id)
references family_tree (person_id);
I have a one-to-many relationship between two classes for this situation. I have a swimming competition and that competition can have x swimmers.
How can I create an SQL table for this, I know I will have to use the Primary Key of Swimmers as a foreign key in the Swimming competition but I have no idea how to represent the correct number of attributes since it's unknown.
This is called a m:n relationship and usually solved with a mapping table.
Something like this:
create table swimmer
(
id integer not null primary key,
lastname varchar(100) not null,
firstname varchar(100)
)
create table competition
(
id integer not null primary key,
name varchar(50) not null,
comp_date date not null
)
create table participant
(
swimmer_id integer not null,
competition_id integer not null,
rank_in_competetion integer,
primary key (swimmer_id, competition_id),
constraint fk_participant_swimmer (swimmer_id) references swimmer(id),
constraint fk_participant_competition (competition_id) references competition(id)
)