SQL query to display names of customers who have purchased all the DVD

These are the tables I have created and inserted the values accordingly:

CREATE TABLE Customer
(Customer_No INTEGER IDENTITY (1,1) PRIMARY KEY,
 Customer_Name VARCHAR(30) NOT NULL
)

CREATE TABLE DVD
(DVD_No INTEGER IDENTITY (1,1) PRIMARY KEY,
 DVD_Name VARCHAR(30)
)

CREATE TABLE DVD_Purchase
(DVD_Purchase_No INTEGER IDENTITY (1,1) PRIMARY KEY,
 DVD_No INTEGER NOT NULL,
 Customer_No INTEGER NOT NULL
 )

INSERT INTO Customer (Customer_Name)
VALUES('Daman')
INSERT INTO Customer (Customer_Name)
VALUES('Saif')
INSERT INTO Customer (Customer_Name)
VALUES('Gurung')
INSERT INTO Customer (Customer_Name)
VALUES('Upendra')

INSERT INTO DVD (DVD_Name)
VALUES('Bleach')
INSERT INTO DVD (DVD_Name)
VALUES('Gintama')
INSERT INTO DVD (DVD_Name)
VALUES('Tokyo Ghoul')
INSERT INTO DVD (DVD_Name)
VALUES('Death Note')

INSERT INTO DVD_Purchase (DVD_No,Customer_No)
VALUES (4,1)
INSERT INTO DVD_Purchase (DVD_No,Customer_No)
VALUES (1,2)
INSERT INTO DVD_Purchase (DVD_No,Customer_No)
VALUES (1,3)
INSERT INTO DVD_Purchase (DVD_No,Customer_No)
VALUES (2,3)
INSERT INTO DVD_Purchase (DVD_No,Customer_No)
VALUES (3,3)
INSERT INTO DVD_Purchase (DVD_No,Customer_No)
VALUES (4,3)
INSERT INTO DVD_Purchase (DVD_No,Customer_No)
VALUES (1,4)
INSERT INTO DVD_Purchase (DVD_No,Customer_No)
VALUES (2,4)

In order to display names of customers who have purchased all the DVD, this is the query that I have tried out:

SELECT Customer_Name
FROM Customer
WHERE 
EXISTS (SELECT Customer_Name,DVD_Name
FROM Customer,DVD,DVD_Purchase
WHERE Customer.Customer_No = DVD_Purchase.Customer_No AND DVD.DVD_No = DVD_Purchase.DVD_No)

But unfortunately, after executing this query it is displaying all the customer names. But I want to display a specific customer name who have purchased all the DVD.

Can someone provide me the correct query ?

You can try something like:

select c.Customer_Name
from Customer c
join (  select Customer_No
        from DVD_Purchase
        group by Customer_No
        having count(distinct DVD_No) = (select count(*) from DVD)
        ) d on c.Customer_No = d.Customer_No

Explaination: first we need to know the number of DVDs available.

select count(*) 
from DVD

Then we need to get the number of distinct DVDs purchased by the customers, and to compare it with the total we got previously.

select Customer_No
from DVD_Purchase
group by Customer_No
having count(distinct DVD_No) = 

And finally, we just need to join with customers table to retrieve the names.

StackExchange Database Administrators Q#184469, answer score: 3