I have created three tables (users, candidates and votes), and when a user create a vote, it is sent to the votes table which has a foreign key candidate from the candidates table, but when I create a new vote, I get this error
ERROR: insert or update on table "votes" violates foreign key constraint "votes_candidate_fkey"
DETAIL: Key (candidate)=(6) is not present in table "candidates".
The candidate table has the candidate with id 6, but when I create a vote I get a foreign key error, how can I solve this, below is the shema
CREATE TABLE IF NOT EXISTS users(
id serial PRIMARY KEY,
first_name VARCHAR (100) NOT NULL,
last_name VARCHAR (100) NOT NULL,
other_name VARCHAR (100) NOT NULL,
email VARCHAR (100) UNIQUE NOT NULL,
password VARCHAR (100) NOT NULL,
phone_Number VARCHAR (100) UNIQUE NOT NULL,
passport_Url VARCHAR (255) NOT NULL,
is_Admin BOOLEAN DEFAULT 'no'
);
CREATE TABLE IF NOT EXISTS candidates(
id serial PRIMARY KEY,
office INTEGER REFERENCES offices(id),
party INTEGER REFERENCES parties(id),
candidate INTEGER UNIQUE REFERENCES users(id)
);
CREATE TABLE IF NOT EXISTS votes(
created_by INTEGER REFERENCES users(id),
office INTEGER REFERENCES offices(id),
candidate INTEGER REFERENCES candidates(id),
created_On DATE NOT NULL DEFAULT NOW(),
PRIMARY KEY (office, created_By)
);
User 6 exists, but you only have five candidates and their ids are 1, 2, 3, 4, and 5.
Your foreign key is to id, not the candidate column:
candidate INTEGER REFERENCES candidates(id),
----------------------------------------^
The appropriate id is 5, for user 6.
You may want to set up the candidates table with the primary key being the user id (that is, candidates are subsets of users). If so remove the serial column:
CREATE TABLE IF NOT EXISTS candidates(
candidate INTEGER PRIMARY KEY REFERENCES users(id),
office INTEGER REFERENCES offices(id),
party INTEGER REFERENCES parties(id)
);
I would recommend this. If you as the database designer are already confused about the difference between a "candidate" and a "user", then no doubt future users of the database will have the same confusion.
The message is very much clear that your candidates tabled does not contain id=6 but you are trying to insert that value into votes tables that's why you got the error, cause it is a foreign key violation
in votes table candidate INTEGER REFERENCES candidates(id) this is relate to candidates tables id column not with candidate column that you thought
Related
I want to be able to find the value using either network_id or username.
Yet the following sintax gives the error of more than one primary key (as expected).
CREATE TABLE Player(
network_id TEXT not null,
username varchar2(50) not null,
value INTEGER,
CONSTRAINT player_pk1 PRIMARY KEY (username),
CONSTRAINT player_pk2 PRIMARY KEY (network_id)
);
Is there a way that I could do this in Sqlite?
A primary key has three components to its definition:
NOT NULL
UNIQUE
Only one per table
That is why you cannot have more than one. But you can have any number of NOT NULL UNIQUE columns:
CREATE TABLE Player(
network_id TEXT not null,
username varchar2(50) not null,
value INTEGER,
CONSTRAINT player_pk1 PRIMARY KEY (username),
CONSTRAINT unq_player_network_id UNIQUE (network_id)
);
I know this question has been asked many times, but none of the answers have solved my issue.
I am creating a database for a uni assignment, using PostgreSQL through pgadmin 4, and I have a table named "staff" populated with staff members with a primary key of "staffid". I then have another table named "client_international", which includes a foreign key of "staffid" which relates to the staff tables primary key.
When trying to insert into the client table, I am getting the following error:
ERROR: insert or update on table "client_international" violates foreign key constraint "intclient_staff_fkey"
DETAIL: Key (staffid)=(100000024) is not present in table "staff".
SQL state: 23503
I am certain that that '100000024' key is in the staff table.. yet I still get the error. Any suggestions? Below I will paste the code I used to create the staff and client tables, in case anyone notices an error in them.
Staff table:
CREATE SEQUENCE staff_seq
start 100000000
increment 1;
CREATE TABLE staff
(
staffid integer default nextval('staff_seq'),
firstname varchar(20) NOT NULL,
lastname varchar(20) NOT NULL,
"position" varchar(20) NOT NULL,
mobile varchar(20) NOT NULL,
email varchar(100) NOT NULL,
"location" integer NOT NULL,
CONSTRAINT staff_pkey PRIMARY KEY (staffid)
);
Client table:
CREATE SEQUENCE client_seq
start 200000000
increment 1;
CREATE TABLE client
(
clientid integer default nextval('client_seq'),
company varchar(100) NOT NULL,
sector varchar(100) NOT NULL,
pointofcontact varchar(20) NOT NULL,
mobile varchar(20) NOT NULL,
email varchar(100) NOT NULL,
approvalstatus boolean default (false),
"location" integer NOT NULL,
staffid integer NOT NULL,
CONSTRAINT client_pkey PRIMARY KEY (clientid)
);
CREATE TABLE client_international
(
CONSTRAINT client_international_pkey PRIMARY KEY (clientid)
) INHERITS ("client");
ALTER TABLE client
ADD CONSTRAINT client_location_fkey FOREIGN KEY ("location") REFERENCES "location" (locationid),
ADD CONSTRAINT client_staff_fkey FOREIGN KEY (staffid) REFERENCES staff (staffid);
ALTER TABLE client_international
ADD CONSTRAINT intclient_location_fkey FOREIGN KEY ("location") REFERENCES "location" (locationid),
ADD CONSTRAINT intclient_staff_fkey FOREIGN KEY (staffid) REFERENCES staff (staffid);
I get the error when running the following statements:
INSERT INTO client_international(company, sector, pointofcontact, mobile, email, approvalstatus, "location", staffid)
VALUES ('Moores Dogs', 'Border Patrol', 'Carol Moore', '07911 653453', 'jenkinsj#k9solutions.co.uk', 'false', '500000001', '100000024');
Here's a screenshot of the entry in the staff table, showing that it's definitely in there:
Foreign keys aren't "inherited".
Quote from the manual
A serious limitation of the inheritance feature is that [...] foreign key constraints only apply to single tables, not to their inheritance children. This is true on both the referencing and referenced sides of a foreign key constraint.
(emphasis mine)
So what you are trying to do, simply isn't supported.
I know that this question has been already answered a million of times, but I couldn't find any solution. Well I have these three tables on postgres sql.
CREATE TABLE user_account (
id SERIAL not null,
firstName VARCHAR(60) not null,
lastName VARCHAR(60) not null,
password VARCHAR(150) not null,
email VARCHAR(40) not null UNIQUE,
isVolunteer BOOLEAN,
complete BOOLEAN,
CONSTRAINT pk_user PRIMARY KEY (id));
CREATE TABLE incident (
id SERIAL not null,
patientId INTEGER not null,
incidentTime VARCHAR(10) not null,
latitude NUMERIC not null,
longitude NUMERIC not null,
city VARCHAR(60) not null,
state VARCHAR(60),
country VARCHAR(60),
complete BOOLEAN,
CONSTRAINT pk_incident PRIMARY KEY (id, patientId),
CONSTRAINT fk_incident FOREIGN KEY (patientId)
REFERENCES user_account (id) MATCH SIMPLE
ON UPDATE CASCADE ON DELETE CASCADE);
CREATE TABLE incident_has_volunteer (
incidentId INTEGER not null,
volunteerId INTEGER not null,
incidentTime VARCHAR(10) not null,
complete BOOLEAN,
CONSTRAINT pk_incident_has_volunteer PRIMARY KEY (incidentId, volunteerId),
CONSTRAINT fk_volunteer FOREIGN KEY (volunteerId)
REFERENCES user_account (id) MATCH SIMPLE
ON UPDATE CASCADE ON DELETE CASCADE,
CONSTRAINT fk_incident FOREIGN KEY (incidentId)
REFERENCES incident (id) MATCH SIMPLE
ON UPDATE CASCADE ON DELETE CASCADE);
When I try to create the table incident_has_volunteer it throws the error there is no unique constraint matching given keys for referenced table "incident".
I tried to add on the third table and the patientId as a foreign key from table incident table but with no luck. I can't understand why it throws this error even if I have already set the primary keys on the incident table.
I'm not an expert in postgres, but I believe that the problem is while fk_incident is referencing incident.id, incident's primary key is made of id + patientId. Since incident.id is guaranteed to be unique only in combination with patientId, there's no way to ensure referential integrity.
I believe that if you add a unique constraint to incident.id (I'm assuming that it would be unique), your foreign key will be legal.
Very simply - one table of primary key acts as a foreign key for another table, so you must ensure that both key is referenced or not.
Simply you will not assign foreign key to the column of another table which does not have primary key. this is called as RDBMS.
Thanks
I have following tables on PostgreSQL 9.4
CREATE TABLE "user" (
id SERIAL PRIMARY KEY,
email CHARACTER VARYING NOT NULL,
password CHARACTER VARYING NOT NULL
);
CREATE TABLE "dealer" (
id SERIAL PRIMARY KEY,
user_id INTEGER NOT NULL REFERENCES "user" (id) ON DELETE RESTRICT
);
CREATE TABLE "affiliate" (
id SERIAL PRIMARY KEY,
user_id INTEGER NOT NULL REFERENCES "user" (id) ON DELETE RESTRICT
);
Is it possible to force user_id value to be unique across tables dealer and affiliate?
There are different setups to use for inheritance in SQL and for this you could just use an integer column type in the table user that marks the type of the user and would reference to table user_type (id,name) that would have the values 1,dealer and 2,affiliate:
CREATE TABLE user_type (
id INTEGER PRIMARY KEY, --could be SERIAL
name text
);
INSERT INTO user_type VALUES (1,'dealer'), (2, 'affiliate');
CREATE TABLE "user" (
id SERIAL PRIMARY KEY,
email CHARACTER VARYING NOT NULL,
password CHARACTER VARYING NOT NULL,
user_type INTEGER REFERENCES user_type NOT NULL,
UNIQUE(id,user_type)
);
This in itself wouldn't force uniqueness across tables so after implementing this you would have the following options:
Drop the tables dealer and affiliate - you won't need them if you rely on the type field to see which one the user is.
If you have to keep those inherited tables you can:
Use triggers - these triggers check the uniqueness and would be actived on INSERT or UPDATE
Another (a bit clumsy) solution: add user_type field to both subtables like this:
CREATE TABLE "dealer" (
id SERIAL PRIMARY KEY,
user_id INTEGER NOT NULL,
user_type INTEGER NOT NULL DEFAULT 1 check (user_type = 1),
FOREIGN KEY (user_id,user_type) REFERENCES "user"(id,user_type) ON DELETE RESTRICT
);
CREATE TABLE "affiliate" (
id SERIAL PRIMARY KEY,
user_id INTEGER NOT NULL,
user_type INTEGER NOT NULL DEFAULT 2 check (user_type = 2),
FOREIGN KEY (user_id,user_type) REFERENCES "user"(id,user_type) ON DELETE RESTRICT
);
The checks and foreign keys together make sure you cannot have both types of user in the main table. Note that user_id might be used as the PRIMARY KEY in the subtables too. Currently a row in user might have several dealer rows linked to it so at least you might want to set user_id foreign keys in subtables as UNIQUE.
I am using PGAdminIII database.
I have one table named STOCKREGISTER which contains composite primary key consisting of three fields ie stockregisterId,applicationId and date.
I have to create another table STOCK which has a foreignkey field that reference the field stockregisterId of STOCKREGISTER.If I am trying to create STOCK table,an error message is shown.The error message is "there is no unique contraint matching keys for referenced table STOCKREGISTER".What another step I have to take next
this first table
CREATE TABLE stock_register
(
stock_register_id bigint NOT NULL,
application_id bigserial NOT NULL,
production_date date NOT NULL,
opening_bal bigint DEFAULT 0,
quantity_produced bigint,
total_quantity bigint
CONSTRAINT primarykey PRIMARY KEY (stock_register_id, application_id, production_date),
CONSTRAINT "foreignKey" FOREIGN KEY (application_id)
REFERENCES application (application_id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
)
below is second table.Here I cannot make stock_register_id as a foreign key
CREATE TABLE Stock
(
stock_id bigint NOT NULL,
stock_register_id bigint,
dimension bigserial NOT NULL,
CONSTRAINT "stockid" PRIMARY KEY (stock_id)
)
I guess that syntax should be:
CREATE TABLE Stock
(
stock_id bigint NOT NULL,
stock_register_id bigint,
dimension bigserial NOT NULL,
CONSTRAINT "stockid"
FOREIGN KEY (stock_id)
REFERENCES stock_register (stock_register_id)
)
CREATE TABLE Stock
(
stock_id bigint NOT NULL,
stock_register_id bigint,
dimension bigserial NOT NULL,
CONSTRAINT primaryKey PRIMARY KEY (stock_id),
CONSTRAINT foreignKey FOREIGN KEY(stock_register_id)
REFERENCES stock_register (stock_register_id)
)
That should be everything you need. You'll also have to make sure the DB table engines, collations and charsets match up when using Foreign Keys.
For the unique constraint issue, there doesn't seem to be a problem with your stock_register_id PK in the stock_register table. Based on the name STOCKREGISTER in the error message I suspect it wasn't finding the table stock_register in your second Create statement.
What is a foreign key? A pointer to a specific record in another table.
How is a specific record in stock_register identified according to your DDL? By the unique combination of (stock_register_id, application_id, production_date).
Therefore stock_register_id = 1 could appear on a thousand different records so long as application_id and production_date are different.
Therefore, if all you have is a stock_register_id, there is no way to know which stock_register record it is pointing to and therefore no way for the DBMS to enforce the foreign key.
You must either add application_id and production_date to the stock table and make all three columns together the FK to the composite key on stock_register, or you must remove application_id and production_date from the PK on stock_register so the FK and PK columns match.