Below are the tables:
CREATE TABLE Person(
PersonID INT PRIMARY KEY,
FirstName VARCHAR(10),
LastName VARCHAR(10));
CREATE TABLE Resources(
ResourceID CHAR(3) PRIMARY KEY
);
CREATE TABLE PR (
PersonID INT,
ResourceID CHAR(3),
CONSTRAINT pkpr PRIMARY KEY (PersonID, ResourceID),
CONSTRAINT fkPersonID FOREIGN KEY (PersonID) REFERENCES Person(PersonID),
CONSTRAINT fkResourceID FOREIGN KEY (ResourceID) REFERENCES Resources(ResourceID));
INSERT INTO Person(PersonID, FirstName, LastName) VALUES (1, 'Bill', 'Smith'),(2, 'John','Jones');
INSERT INTO Resources (ResourceID) VALUES ('ABC'),('DEF'),('HIJ');
INSERT INTO PR (PersonID, ResourceID) VALUES (1,'ABC'),(1,'DEF'),(2,'ABC'), (2,'HIJ'), (1,'HIJ');
How to find all the persons which has resources ('ABC', 'DEF') ?
With above inserted data it should return person Bill Smith
I am using PostgreSql.
You can use aggregation:
select pr.personid
from pr
where pr.resourceid in ('ABC', 'DEF')
group by pr.personid
having count(*) = 2;
The primary key on pr prevents duplicates, so count(*) ensures that both resources are assigned to the person.
Related
when i try enter the last part of code i get the error message "error code : 1452 cannot add or update a child row a foreign key constraint fails"
CREATE TABLE products (
id int auto_increment primary key,
name varchar (30),
price decimal(3,2),
coffee_origin varchar (30)
);
CREATE TABLE customers (
id INT AUTO_INCREMENT PRIMARY KEY,
first_name VARCHAR(30),
last_name VARCHAR (30),
gender ENUM ('M','F'),
phone_number VARCHAR(11)
);
CREATE TABLE orders(
id INT AUTO_INCREMENT PRIMARY KEY,
product_id INT,
customer_id INT,
order_time DATETIME,
FOREIGN KEY (product_id) REFERENCES products(id),
FOREIGN KEY (customer_id) REFERENCES customers(id)
);
INSERT INTO orders (product_id,customer_id,order_time) VALUES (1,1,'2017-01-01 08-02-11');
In order to be able to insert your values into the orders table, I think you might need to add rows to your products and customers tables.
Here are possible examples of how you could add rows to your products and customers tables:
insert into products (name, price, coffee_origin) values ('Dark Blend', 4.99, 'Brazil');
insert into customers (first_name, last_name, gender, phone_number) values ('First Name', 'Last Name', 'M', '123-456-7890');
Then, you can find the id values that you might need to use for your final insert action by running the following queries:
select id from products where name = 'Dark Blend';
select id from customers where phone_number = '123-456-7890';
Finally, you can try running your insert action again, but this time using the id values from the queries above this; maybe like this, if you get back 1 for the ids of each of those queries above:
insert into orders (product_id, customer_id, order_time) values (1, 1, '2021-01-01 00:00:00');
Lets say I have two many-to-many relations called Tutors and Assits. They are both connected courses. If they are both inheritance of relation called Staff they both have the same primary keys. That would mean the many-to-many relation will also have the same primary keys.
If I have two relations with the same primary keys what do I do? Here is an example of the table:
It should be pretty simple to add those two relationships. For example:
create table staff (
id int primary key not null,
name varchar(20)
);
create table tutor (
id int primary key not null,
office_number varchar(10),
foreign key (id) references staff (id)
);
create table assistant (
id int primary key not null,
title varchar(20),
foreign key (id) references staff (id)
);
create table course (
course_id int not null,
year int not null,
semester int not null,
primary key (course_id, year, semester),
tutor_id int not null references tutor (id),
assistant_id int not null references assistant (id)
);
Now, if you insert some data:
insert into staff (id, name) values (1, 'Alice');
insert into staff (id, name) values (2, 'Victor');
insert into tutor (id, office_number) values (1, '101-A');
insert into assistant (id, title) values (2, 'Adjunct Professor');
insert into course (course_id, year, semester, tutor_id, assistant_id)
values (101, 2020, 1, 1, 2);
You can run a query over it:
select
c.course_id, c.year, c.semester,
ts.name as tutor, t.office_number,
ta.name as assistant, a.title
from course c
join tutor t on c.tutor_id = t.id
join staff ts on ts.id = t.id
join assistant a on c.assistant_id = a.id
join staff ta on ta.id = a.id
Result:
course_id year semester tutor office_number assistant title
---------- ----- --------- ------ -------------- ---------- -----------------
101 2020 1 Alice 101-A Victor Adjunct Professor
See running example at DB Fiddle.
If the relation course - tutor is a many-to-many relation you will need an extra xref table:
course -|---|< course_tutor >0---|- tutor
The same thing for assistant.
Even when the same person is tutor and assistant in the same course there will be a record in course_tutor and course_assistant with the same course_id and staff_id but that is not a problem.
Find the names and addresses of the customers with the highest balance and the people with the lowest loan in each branch.
Tables:
CREATE TABLE Branch(
BranchID INT NOT NULL,
Address varchar(100),
ManagerSsn varchar(100),
Branch_name varchar(255),
PRIMARY KEY (BranchID)
);
CREATE TABLE Has_Account(
Assn Int,
ANo CHAR(16),
Opened_date date,
PRIMARY KEY(Assn),
FOREIGN KEY(Assn) REFERENCES Customer(Ssn),
FOREIGN KEY(ANo) REFERENCES Account(AccountNo)
);
CREATE TABLE Account(
AccountNo CHAR(16) NOT NULL,
BranchID Int,
Balance Int,
PRIMARY KEY(AccountNo),
FOREIGN KEY(BranchID) REFERENCES Branch(BranchID)
);
CREATE TABLE Customer(
Ssn Int CHECK(0101000000000 < Ssn < 3112999995999) NOT NULL,
Address VARCHAR(100),
Name VARCHAR(100),
EmployerID Int,
PRIMARY KEY(Ssn)
);
CREATE TABLE Loan(
LoanNo CHAR(16) NOT NULL,
BranchID Int,
Amount Int,
PRIMARY KEY(LoanNo),
FOREIGN KEY(BranchID) REFERENCES Branch(BranchID)
);
CREATE TABLE Has_Loan(
LNo CHAR(16),
Lssn Int,
Repay_date date,
PRIMARY KEY (LNo),
FOREIGN KEY(Lno) REFERENCES Loan(LoanNo),
FOREIGN KEY(Lssn) REFERENCES Customer(Ssn)
);
Populating the tables
INSERT INTO CUSTOMER
VALUES('2004980890999', ‘Kanaribakken 2B’, ‘Paul Stolten’, ‘’);
INSERT INTO CUSTOMER
VALUES(‘1010968250234’, ‘Parkveien 5’, ‘Anders Nilsson’, ‘’, );
INSERT INTO CUSTOMER
VALUES(‘2104996495987’, ‘Kongeveien 24B’, ‘Karoline Torskerud’, ‘123’, );
INSERT INTO CUSTOMER
VALUES(‘2910943135444’, ‘Gåsesmauet 3’, ‘Bente Arildsen’, ‘555’, );
INSERT INTO CUSTOMER
VALUES(‘1304980890678’, ‘Knallebakken 30’, ‘Knut Solberg’, ‘555’,);
INSERT INTO CUSTOMER
VALUES('1019730000234', ‘Laksebakken 40’, ‘Harald Olsen’, ‘’);
INSERT INTO BRANCH
VALUES (‘123’, ‘Børsveien 49’, ‘1412963670786’, ‘Nesttun’,);
INSERT INTO BRANCH
VALUES(‘555’, ‘Vimpelveien 24’, ‘2412983905999’, ‘DNB’,);
INSERT INTO ACCOUNT
VALUES (‘1234567890087620’, ‘123’, ‘459’,);
INSERT INTO ACCOUNT
VALUES (‘8402849284910340’, ‘123’, ‘35120’,);
INSERT INTO ACCOUNT
VALUES (‘3452948293817280’, ‘555’, ‘69’,);
INSERT INTO HAS_ACCOUNT
VALUES(‘1010968250234’, ‘1234567890087620’, ‘17.04.2012’,);
INSERT INTO HAS_ACCOUNT
VALUES (‘2104996495987’, ‘8402849284910340’, ‘20.09.2000’,);
INSERT INTO HAS_ACCOUNT
VALUES (‘2910943135444’, ‘3452948293817280’, ‘29.01.2006’,);
INSERT INTO LOAN
VALUES (‘2291928394039280’, ‘555’, ‘50000’,);
INSERT INTO LOAN
VALUES (‘1295829384932100’, ‘123’, ‘400000’,);
INSERT INTO LOAN
VALUES ('1295829384932222', ‘123’, ‘40000’);
INSERT INTO HAS_LOAN
VALUES (‘2910943135444’, ‘2291928394039280’, ‘09.09.2019’,);
INSERT INTO HAS_LOAN
VALUES (‘2104996495987’, ‘1295829384932100’, ‘14.03.2022’,);
INSERT INTO HAS_LOAN
VALUES ('2004980890999', '1295829384932222', '01.02.2021');
Draft so far:
SELECT DISTINCT Customer.Name, Customer.Address
FROM Customer, Account, Loan, Has_Account, Has_Loan
WHERE Customer.Ssn = Has_Account.Assn AND Has_Account.Assn = Has_Loan.Lssn
(SELECT Account.Balance MAX(Balance) GROUP BY(BranchID)) AND
Loan.AMOUNT(SELECT Loan.Amount MIN(Amount) GROUP BY(BranchID));
I think it is correct that we need to group our output by BranchID, and max/min is ok. Looks like the statement formalities are wrong somehow.
Any help or hint is much appreciated!
SQL Error
I'm not sure what I did wrong here
Here is the DDL I used to create my tables
Create Table HomeState (StateAbbreviation char(2) Primary Key,
StateName varchar(25));
Create Table Country (CountryAbbreviation char(2) Primary Key,
CountryName varchar(35));
Create Table Employee (EmployeeID Integer Primary Key NOT NULL,
FirstName varchar(20),
LastName varchar(30),
MI char(1),
HomeAddress varchar(30),
Zip char(5),
DateOfBirth date,
HireDate date,
TerminationDate date,
AnnualSalary number(20,2),
LicenseDate date,
StateAbbreviation char(2),
CountryAbbreviation char(2),
Foreign Key (StateAbbreviation) references HomeState,
Foreign Key (CountryAbbreviation) references Country);
Create Table Truck (VinNumber Integer Primary Key,
Make varchar(25),
Model varchar(30),
Year Integer,
PurchasePrice number(20,2),
LicenseNumber varchar(15));
Create Table EmployeeTruck (EmployeeID Integer,
VinNumber Integer,
Primary Key(EmployeeID,VinNumber),
Foreign Key (EmployeeID) references Employee,
Foreign Key (VinNumber) references Truck);
Create Table Accident (AccidentID Integer Primary Key,
DateOfAccident date,
AccidentDescription varchar(200),
AccidentLocation varchar(100),
EmployeeID Integer,
Foreign Key (EmployeeID) references Employee);
and here is the command i used to try and fill in the employee table
insert into employee
values ('1','brian','kim','j','adfasdf',
'1234','24-nov-1993','24-sep-1993','24-sep-1993',
'1234','24-sep-1993','as','as')
but it always gives me the error i put as the title of this question...
In the table "Employee", you say that Foreign Key (StateAbbreviation) references HomeState, and Foreign Key (CountryAbbreviation) references Country). The values you insert into Employee.HomeState and Employee.CountryAbbreviation have to exist in the tables HomeState and Country before you can insert into Employee.
Insert rows into HomeState and Country before you insert into Employee.
You have other problems, too. Here's an example.
Create Table HomeState (StateAbbreviation char(2) Primary Key,
StateName varchar(25));
insert into HomeState values ('AL', 'Alabama');
insert into HomeState values ('AM', 'Alabama');
insert into HomeState values ('AN', 'Alabama');
All those insert statements succeed. They shouldn't. In this case, StateName is also a candidate key.
Create Table HomeState (
StateAbbreviation char(2) Primary Key,
StateName varchar(25) not null unique
);
Let's take this a little further.
Create Table HomeState (
StateAbbreviation char(2) Primary Key,
StateName varchar(25) not null unique
);
Create Table Country (
CountryAbbreviation char(2) Primary Key,
CountryName varchar(35) not null unique
);
insert into HomeState values ('CA', 'California');
insert into Country values ('AF', 'Afghanistan');
insert into Employee (EmployeeID, StateAbbreviation, CountryAbbreviation)
values (-42, 'CA', 'AF');
The state "California, US" makes sense. The state "California, Afghanistan" doesn't.
An employee having no name doesn't make sense. Declare FirstName, LastName, and HireDate not null.
Bet on this: whatever nonsense your database allows will appear. It's just a matter of time.
I have searched for an answer but am not finding it. I have 2 tables. Both have an auto-generated PK. The PK from table 2 is an FK in table 1. Since they are both auto-generated I assumed the FK in table 1 would populate with the value that is auto-generated from table 2 but it is not working. The FK in table 1 ends up null. Here is my SQL code for creating table 1:
CREATE TABLE Employee_tbl (
EmployeeID int PRIMARY KEY IDENTITY,
LastName varchar(20) not null,
FirstName varchar(20) not null,
Age varchar(3) not null,
JobID int FOREIGN KEY REFERENCES JobTitle_tbl(JobID),
)
and here is table 2:
create table JobTitle_tbl(
JobID int PRIMARY KEY IDENTITY,
EEO1Classification varchar(50) not null,
Exempt_nonexempt_status varchar(20) not null,
)
I also have some insert statements:
INSERT INTO Employee_tbl
(LastName, FirstName, Age)
Values
('Smith', 'John', '50'),
...
and:
INSERT into JobTitle_tbl (EEO1Classification, Job_title, )
VALUES ('Office/Clerical', 'Accounting Clerk', ),
Why is the FK value showing null when I query table 1?
The foreign keys will not auto-populate, as it doesn't know what foreign key to use. You need to either insert the rows into the JobTitle_tbl table, then select the IDs back out (or use ##identity if using sql server)
select id from JobTitle_tbl where Job_title = ''
Another option would be to update your insert statements to include the primary key, although you'll have to allow identity inserts first.
SET IDENTITY_INSERT JobTitle_tbl ON
into the JobTitle_tbl (id, title) values (1, 'Manager')
SET IDENTITY_INSERT JobTitle_tbl OFF
In either case, you'll need to then update your first insert statements with the ID that you have.
insert into Employee_tbl (LastName, FirstName, JobID) values ('Smith', 'John', 1)