I am getting an error when i create my tabels.
The problem is that AssCode is not unique, so i can set it to unique, the combination of courseCode and AssCode is unique, thats why they are set as primary keys. I am using postgressql
here is the error:
ERROR: there is no unique constraint matching given keys for referenced table "assignments"
SQL state: 42830
here is my code:
CREATE TABLE Teachers (
BSN int primary key,
Surname varchar(40) NOT NULL,
Name varchar(40) NOT NULL
);
CREATE TABLE Courses (
CourseCode varchar(10) primary key,
Name varchar(20) NOT NULL
);
CREATE TABLE Assignments (
CourseCode varchar(10) REFERENCES Courses ON DELETE CASCADE,
AssCode varchar(10),
primary key(CourseCode,AssCode),
DependOn varchar(10),
Year date,
week int
);
CREATE TABLE WorkOn (
BSN int REFERENCES Teachers(BSN),
CourseCode varchar(10) REFERENCES Assignments(CourseCode),
AssCode varchar(10) REFERENCES Assignments(AssCode),
primary key (CourseCode,BSN,AssCode)
);
I found the answer:
CREATE TABLE WorkOn (
BSN int primary key REFERENCES Teachers(BSN),
CourseCode varchar(10),
AssCode varchar(10),
foreign key (CourseCode, AssCode) references Assignments (CourseCode, AssCode)
);
Related
create database my_data
create table tblperson(
pid int primary key,
pname varchar(15),
pgender varchar(15)
)
create table tblgender(
gid varchar(15) primary key,
gender varchar(15)
)
Alter table tblperson add constraint giFK
Foreign key (pgender) references tblgender(gid)
CREATE TABLE student
(
student_id INT PRIMARY KEY,
first_name VARCHAR(40) NOT NULL,
last_name VARCHAR(40) NOT NULL,
birth_day DATE NOT NULL,
sex VARCHAR(1) NOT NULL,
student_email_address VARCHAR(40) NOT NULL UNIQUE,
student_password VARCHAR(10) NOT NULL UNIQUE,
student_nick_name VARCHAR(10) NOT NULL,
student_qualification VARCHAR(10) NOT NULL,
student_documents VARCHAR(255) NOT NULL,
student_image VARCHAR(100) NOT NULL
);
CREATE TABLE student_feedback
(
sr_no BIGSERIAL PRIMARY KEY,
student_id INT NOT NULL,
feedback_type VARCHAR(10) NOT NULL,
feedback_text VARCHAR(200) NOT NULL,
FOREIGN KEY (student_id) REFERENCES student(student_id)
);
CREATE TABLE online_exam
(
exam_id INT PRIMARY KEY,
exam_title VARCHAR(20) UNIQUE NOT NULL,
exam_duration_min INT NOT NULL,
total_questions INT NOT NULL,
marks_per_right_answer INT NOT NULL,
marks_per_wrong_answer INT NOT NULL,
passing_marks INT NOT NULL,
exam_status VARCHAR(2)
);
CREATE TABLE exam_subjects
(
sub_id INT,
exam_id INT,
sub_name VARCHAR(20) NOT NULL,
sub_desc VARCHAR(20) NOT NULL,
UNIQUE(sub_id,exam_id),
PRIMARY KEY(sub_id,exam_id),
FOREIGN KEY (exam_id) REFERENCES online_exam(exam_id) ON DELETE CASCADE
);
CREATE TABLE sub_questions
(
sub_id1 INT,
ques_id INT,
ques_text VARCHAR(150) NOT NULL,
ques_attachments VARCHAR(255),
option_1 VARCHAR(20) NOT NULL,
option_2 VARCHAR(20) NOT NULL,
option_3 VARCHAR(20) NOT NULL,
option_4 VARCHAR(20) NOT NULL,
UNIQUE(sub_id1,ques_id),
PRIMARY KEY (sub_id1,ques_id),
FOREIGN KEY (sub_id1) REFERENCES exam_subjects(sub_id) ON DELETE CASCADE
);
CREATE TABLE ques_answers
(
ans_id INT,
ques_id INT,
ans VARCHAR(20) NOT NULL,
PRIMARY KEY (ans_id,ques_id),
FOREIGN KEY (ques_id) REFERENCES sub_questions(ques_id) ON DELETE CASCADE
);
CREATE TABLE exam_registration
(
student_id INT,
exam_id INT,
exam_date_time TIMESTAMP NOT NULL,
PRIMARY KEY (student_id,exam_id),
FOREIGN KEY (student_id) REFERENCES student(student_id) ON DELETE CASCADE,
FOREIGN KEY (exam_id) REFERENCES online_exam(exam_id) ON DELETE CASCADE
);
CREATE TABLE exam_result
(
student_id INT,
exam_id INT,
sub_id INT,
marks_scored INT NOT NULL,
correct_ques INT NOT NULL,
wrong_ques INT NOT NULL,
grade VARCHAR(10) NOT NULL,
PRIMARY KEY(student_id,exam_id,sub_id),
FOREIGN KEY (student_id) REFERENCES student(student_id) ON DELETE CASCADE,
FOREIGN KEY (exam_id) REFERENCES online_exam(exam_id) ON DELETE CASCADE,
FOREIGN KEY (sub_id) REFERENCES exam_subjects(sub_id) ON DELETE CASCADE
);
Output :
CREATE TABLE,
CREATE TABLE,
CREATE TABLE,
CREATE TABLE,
There is no unique constraint matching given keys for referenced table "exam_subjects", relation "sub_questions" do not exist,
CREATE TABLE,
There is no unique constraint matching given keys for referenced table "exam_subjects".
Why am I getting "there is no unique..." error in postgresql? How to solve it? Please help.
In your table exam_subjects the primary key is a compossed key (PRIMARY KEY(sub_id, exam_id))
Therefore, your table sub_questions must have both columns to create the constraint, otherwise you get the error about unique constraints (or you can create a unique field acting as primary key, and create a unique index on both columns sub_id and exam_id)
Would appreciate help. Can not create the "Teaches" and "takes" table.
CREATE DATABASE university;
use university;
CREATE TABLE classroom(
building VARCHAR(20),
room_number INT,
capacity INT,
PRIMARY KEY (building,room_number)
) ;
CREATE TABLE Sales(
item VARCHAR(20),
color VARCHAR(20),
clothes_size VARCHAR(20),
quantity INT,
PRIMARY KEY (item,color,clothes_size,quantity)
);
CREATE TABLE Department (
dept_name VARCHAR(20),
building VARCHAR(20),
budget INT,
FOREIGN KEY (building) references classroom(building),
PRIMARY KEY (dept_name,building,budget)
);
CREATE TABLE Course (
course_id VARCHAR(20)PRIMARY KEY,
title VARCHAR(20),
dept_name VARCHAR(20),
credits INT,
FOREIGN KEY (dept_name) references Department(dept_name)
);
CREATE TABLE Instructor(
ID VARCHAR(20) PRIMARY KEY,
neme VARCHAR(20),
dept_name VARCHAR(20),
salary INT,
FOREIGN KEY (dept_name) references Department(dept_name)
);
CREATE TABLE section(
course_id VARCHAR(20),
sec_id INT,
semester VARCHAR(20),
year1 INT,
building1 VARCHAR(20),
room_number INT,
time_slot_id CHAR,
FOREIGN KEY (course_id) REFERENCES Course(course_id),
FOREIGN KEY (building1,room_number) references classroom(building,room_number),
PRIMARY KEY(course_id,sec_id,semester,year1)
);
CREATE TABLE Teaches(
ID VARCHAR(20),
course_id VARCHAR(20),
sec_id VARCHAR(20),
semester VARCHAR(20),
year1 INT,
FOREIGN KEY (ID) references Instructor(ID),
FOREIGN KEY (sec_id) references section(sec_id),
FOREIGN KEY (semester,year1) references section(semester,year1),
FOREIGN KEY (course_id) references course(course_id),
PRIMARY KEY (ID,course_id,sec_id,year1,semester)
);
CREATE TABLE student(
ID VARCHAR(20) PRIMARY KEY,
name1 VARCHAR(20),
dept_name VARCHAR(20),
tot_cred INT);
CREATE TABLE Takes(
ID VARCHAR(20),
course_id VARCHAR(20),
sec_id INT,
semester VARCHAR(20),
year1 INT,
grade char,
FOREIGN KEY (ID) references student(ID),
FOREIGN KEY (sec_id) references section(sec_id),
FOREIGN KEY (semester) references section(semester),
FOREIGN KEY (year1) references section(year1),
FOREIGN KEY (course_id) references course(course_id),
PRIMARY KEY(ID,sec_id,semester,year1,course_id)
);
Foreign key references need to have the same types as the primary keys they refer to. So consider:
CREATE TABLE Department (
dept_name VARCHAR(20),
building VARCHAR(20),
budget INT,
FOREIGN KEY (building) references classroom(building),
PRIMARY KEY (dept_name,building,budget)
);
CREATE TABLE Instructor (
ID VARCHAR(20) PRIMARY KEY,
neme VARCHAR(20),
dept_name VARCHAR(20),
salary INT,
FOREIGN KEY (dept_name) references Department(dept_name)
);
The primary key for Department has three components -- dept_name, building, budget. However, the reference has only one component. They cannot match; the number is not correct, much less the types.
I would recommend that you use auto-incremented ids for your primary keys. You can also specify uniqueness constraints, if you like. So for this small example:
create table buildings (
building_id int auto_increment primary key,
building varchar(20),
constraint unq_buildings_building unique(building)
);
create table classrooms (
classroom_id int auto_increment primary key,
building_id int,
room_number int,
capacity int,
constraint fk_classrooms_building_id foreign key (building_id) references buildings (building_id)
) ;
create table Departments (
department_id int auto_increment primary key,
dept_name varchar(20),
building_id int,
budget INT,
constraint fk_departments_building_id foreign key (building_id) references buildings(building_id)
);
create table instructors (
instructor_id int auto_increment primary key,
id varchar(20) unique,
name varchar(20),
department_id int,
salary int,
foreign key instructors_department_id foreign key (department_id) references departments (department_id)
);
This is just a small sample of your tables. But the following are some rules that I follow:
Table names are plural.
They have a primary key which is the singular form followed by _id (or Id).
Foreign key references are only to primary keys.
To the extent possible, foreign keys and primary keys have the exact same name.
Explicit constraints are given names. The names follow a very precise naming convention.
I also added a buildings table. It is referenced in at least two places, so it seems worthy of being its own entity.
This should give you some ideas on how to build your database.
For some reason I'm getting an error* in my code. I'm quite new to PostgreSQL, and simply SQL. What is causing this error?
*there is no unique constraint matching given keys for referenced table "tech".
BEGIN;
CREATE TABLE Person (
person_id SERIAL PRIMARY KEY,
firstname VARCHAR(128),
lastname VARCHAR(128),
email_adr VARCHAR(128),
UNIQUE(person_id, email_adr)
);
CREATE TABLE Phone (
person_id INT REFERENCES Person(person_id),
phone_nr INT PRIMARY KEY,
UNIQUE(phone_nr)
);
CREATE TABLE Tech (
tech_id INT REFERENCES Person(person_id),
username VARCHAR(80) PRIMARY KEY,
password VARCHAR(80) NOT NULL,
location Varchar(128),
UNIQUE(username, tech_id)
);
CREATE TABLE Customer (
customer_id INT REFERENCES Persons(person_id),
addresse VARCHAR(255) NOT NULL,
UNIQUE(customer_id)
);
CREATE TABLE Task (
task_id SERIAL PRIMARY KEY,
payment MONEY,
tech INT REFERENCES Tech(tech_id) NOT NULL,
customer INT REFERENCES Customer(customer_id) NOT NULL,
start_date DATE NOT NULL,
end_dato DATE,
UNIQUE(tech, customer, start_date, end_date)
);
COMMIT;
In table Task you trying to reference to table Tech by tech_id. To do that you must add UNIQUE CONSTRAINT to tech_id in Tech.
Right now in table Tech you have UNIQUE(username, tech_id) that means that values in column tech_id could by doubled Ex.
Tech
-------------------------------
tech_id username, ....
------------------------------
1 'John'
2 'Tony'
1 'Nataly'
Acctually the better idea is to set reference by PRIMARY KEY, so in your case username in table Tech.
If you want to leave structure the way present in question, you should just add UNIQUE(tech_id) in column Tech.
What do you think of this code?
BEGIN;
CREATE TABLE Person (
person_id SERIAL PRIMARY KEY,
firstname VARCHAR(128),
lastname VARCHAR(128),
email_adr VARCHAR(128),
UNIQUE(person_id),
UNIQUE(email_adr)
);
CREATE TABLE Phone (
person_id INT,
phone_nr INT PRIMARY KEY,
);
CREATE TABLE Tech (
tech_id INT,
username VARCHAR(80) PRIMARY KEY,
password VARCHAR(80) NOT NULL,
location Varchar(128),
FOREIGN KEY(tech_id) REFERENCES Person(person_id),
UNIQUE(username),
UNIQUE(tech_id)
);
CREATE TABLE Customer (
customer_id INT REFERENCES Persons(person_id),
addresse VARCHAR(255) NOT NULL,
FOREIGN KEY(tech_id) REFERENCES Person(person_id),
UNIQUE(customer_id)
);
CREATE TABLE Task (
task_id SERIAL PRIMARY KEY,
payment MONEY,
tech varchar(80) REFERENCES Tech(username) NOT NULL,
customer INT REFERENCES Customer(customer_id) NOT NULL,
start_date DATE NOT NULL,
end_dato DATE,
UNIQUE(tech, customer, start_date, end_date)
);
COMMIT;
This question already has an answer here:
ORA-00907: missing right parenthesis
(1 answer)
Closed 8 years ago.
I tried to create Foreign key and PRIMARY KEY
My code is ok with Table1
CREATE TABLE Persons
(
P_Id int NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255)
);
Table2:
CREATE TABLE Orders
(
O_Id int NOT NULL PRIMARY KEY,
OrderNo int(10),
P_Id int FOREIGN KEY REFERENCES Persons(P_Id)
);
error :-ORA-00907: missing right parenthesis
Don't know what the error is.
When you declare the FK "inline" you must not specify the foreign key keyword:
CREATE TABLE Orders
(
O_Id int NOT NULL PRIMARY KEY,
OrderNo int(10),
P_Id int REFERENCES Persons(P_Id)
);
Btw: you don't even need to list the column name when using an inline definition, P_Id int REFERENCES Persons would be enough.
That will generate a system-named constraint (e.g. SYS_C0066866), so it's generally better to use a format where you can specify the name of the constraint:
CREATE TABLE Orders
(
O_Id int NOT NULL PRIMARY KEY,
OrderNo int(10),
P_Id int,
constraint fk_orders_person foreign key (p_id) REFERENCES Persons(P_Id)
);
If you're inlining your foreign key definition in the column's definition, you don't need the foreign key phrase:
CREATE TABLE Orders
(
O_Id int NOT NULL PRIMARY KEY,
OrderNo int(10),
P_Id int REFERENCES Persons(P_Id)
);
For MySql
CREATE TABLE Orders
(
O_Id int NOT NULL PRIMARY KEY,
OrderNo int(10),
P_Id int,
FOREIGN KEY(P_Id) REFERENCES Persons(P_Id)
);
For SQL
CREATE TABLE Orders
(
O_Id int NOT NULL PRIMARY KEY,
OrderNo int(10),
P_Id int FOREIGN KEY REFERENCES Persons(P_Id)
);
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