Tables

CREATE TABLE YELP_USER (
    Yelp_ID VARCHAR(10) PRIMARY KEY,
    Email VARCHAR(30) NOT NULL,
    FN VARCHAR(10) NOT NULL,
    LN VARCHAR(10) NOT NULL,
    DOB DATE NOT NULL,
    BirthPlace VARCHAR(30) NOT NULL,
    Gender CHAR NOT NULL
);

CREATE TABLE BUNCATEGORY (
    Category_ID VARCHAR(10) PRIMARY KEY,
    CategoryNamne VARCHAR(30) NOT NULL
);

CREATE TABLE BUSINESS (
    Business_ID VARCHAR(10) PRIMARY KEY,
    BusinessName VARCHAR(50) NOT NULL,
    City VARCHAR(20) NOT NULL,
    StateName VARCHAR(20) NOT NULL,
    Phone VARCHAR(14) NOT NULL,
    Category_ID VARCHAR(10) NOT NULL,
    OPENED CHAR NOT NULL,
    FOREIGN KEY (Category_ID) REFERENCES BUNCATEGORY(Category_ID) ON DELETE SET NULL 
);

CREATE TABLE REVIEWS (
    Review_ID VARCHAR(10) PRIMARY KEY,
    Rating Number(1) NOT NULL,
    Author VARCHAR(10) NOT NULL,
    Publish_Date DATE NOT NULL,
    Rec_NotREC CHAR NOT NULL,
    Business_ID VARCHAR(10) NOT NULL,
    Votes_Funny NUMBER NOT NULL,
    Votes_Cool NUMBER NOT NULL,
    Votes_Useful NUMBER NOT NULL,
    FOREIGN KEY (Author) REFERENCES YELP_USER(Yelp_ID) ON DELETE SET NULL , 
    FOREIGN KEY (Business_ID) REFERENCES BUSINESS(Business_ID) ON DELETE SET NULL
);

Queries

Get the businesses in San Jose, CA that are still “in business”. Results should be sorted by
review counts in descending order. Return for the top 7 businesses, the business id, name,
review count, and average rating of the business.

SELECT* 
FROM (
	SELECT B.Business_ID, B.BusinessName, COUNT(B.Business_ID) as count, AVG(R.Rating)
	FROM BUSINESS B, REVIEWS R
	WHERE B.City = 'San Jose' AND B.StateName = 'CA' AND B.OPENED = 'T' AND R.Business_ID = B.Business_ID
	GROUP BY B.Business_ID, B.BusinessName
	ORDER BY count DESC
) 
WHERE ROWNUM <= 7;

Get the review counts for businesses in each business category. Results should be sorted by
the review counts in descending order.

SELECT B.Category_ID, B.Business_ID,COUNT(B.Business_ID) as CN
FROM BUSINESS B, REVIEWS R
WHERE  B.Business_ID = R.Business_ID
GROUP BY B.Business_ID, B.Category_ID
ORDER BY CN DESC;

Find the average rating across all reviews written by a particular user.

SELECT Y.Yelp_ID, nvl(AVG(R.Rating),0) 
FROM  REVIEWS R, YELP_USER Y
WHERE R.Author(+) = Y.Yelp_ID
GROUP BY Y.Yelp_ID;

Get the businesses in San Jose, CA that have been reviewed by more than 5 elite' users. Users who have written more than 10 reviews are calledelite’ users. Results should be
ordered by the elite' user count in descending order. Return for the top 5 businesses, the business id, business name, business review count, average rating, and the count of theelite’
users for the particular business.

SELECT *
FROM (
SELECT T.Business_ID, TT.BusinessName, T.Review_Count, T.Avg_Rating, TT.elite
FROM
(
SELECT R.Business_ID as Business_ID, COUNT(R.Review_ID) as Review_Count, AVG(R.Rating) as Avg_Rating
FROM Reviews R
WHERE R.Business_ID in (
		SELECT B.Business_ID
		FROM  BUSINESS B, REVIEWS R 
		WHERE B.City = 'San Jose' 
		AND B.StateName = 'CA' 
		AND R.Business_ID = B.Business_ID
		AND R.Author in (
			SELECT T1.Author
			FROM (
				SELECT R.Author Author, COUNT(R.Review_ID) as CN
				FROM Reviews R
				Group By R.Author
			) T1
			WHERE CN > 10
		)
		GROUP BY B.Business_ID
		HAVING COUNT(R.Author) > 5
)
GROUP BY (R.Business_ID)
) T,
(
SELECT B.Business_ID as Business_ID, B.BusinessName as BusinessName,COUNT(R.Author) as elite
FROM  BUSINESS B, REVIEWS R 
WHERE B.City = 'San Jose' 
AND B.StateName = 'CA' 
AND R.Business_ID = B.Business_ID
AND R.Author in (
	SELECT T2.Author
	FROM (
		SELECT R.Author Author, COUNT(R.Review_ID) as CN
		FROM Reviews R
		Group By R.Author
	) T2
	WHERE CN > 10
)
GROUP BY B.Business_ID,B.BusinessName
HAVING COUNT(R.Author) > 5
	) TT
WHERE TT.Business_ID = T.Business_ID
ORDER BY TT.elite
) 
WHERE ROWNUM <= 5;

Get the businesses in San Jose, CA that have the highest percentage of reviews with rating of
5, and have been reviewed at least 5 times. Results should be ordered by the percentage in
descending order. Return for the top 5 businesses, the business id, business name, review
count, and percentage of reviews with rating of 5.

SELECT * 
FROM (
SELECT T.Business_ID, COUNT(T.BUSINESS_ID), ((T.five/COUNT(T.BUSINESS_ID))*100) percent
FROM ( 
	SELECT R.Business_ID, COUNT(R.Business_ID) as five
	FROM REVIEWS R
	WHERE R.Rating = 5
	GROUP BY R.Business_ID
	) T, Reviews R
WHERE T.Business_ID = R.Business_ID
AND T.Business_ID in (
	SELECT B.Business_ID
	FROM BUSINESS B, REVIEWS R
	WHERE B.City = 'San Jose'
	AND B.StateName = 'CA'
	AND B.Business_ID = R.Business_ID
	GROUP BY B.Business_ID
	HAVING COUNT(R.Review_ID) >= 5
	)
GROUP BY T.Business_ID, T.five
ORDER BY percent DESC
) WHERE ROWNUM <= 5;

Find top two businesses, which have highest average ratings in each business category. For
each business, list business id, business name and business category name.

SELECT TT.business_ID, TT.BusinessName, TT.categoryname
FROM (SELECT T.Business_ID as business_ID, T.BusinessName as businessname, T.rate, C.CategoryNamne as categoryname,
	ROW_NUMBER() OVER (PARTITION BY T.Category_ID Order by T.rate DESC) AS ranking 
	FROM (
		SELECT B.Business_ID Business_ID, B.BusinessName BusinessName, B.Category_ID Category_ID, AVG(R.Rating) as rate
		FROM BUSINESS B, REVIEWS R
		WHERE  B.Business_ID = R.Business_ID
		GROUP BY B.Business_ID, B.BusinessName, B.Category_ID
	) T, BUNCATEGORY C
	WHERE T.Category_ID = C.Category_ID
) TT
WHERE ranking <= 2;

Find the oldest user who never reviewed any businesses.

SELECT * 
	FROM (
	SELECT Y.Yelp_ID, Y.DOB as birthday
	FROM YELP_USER Y
	WHERE Y.Yelp_ID not in (
		SELECT R.Author
		FROM Reviews R
		GROUP BY R.Author
	)
	ORDER BY birthday
)
WHERE ROWNUM <= 1;

Find every business in CA that has the word “Coffee” in its name.

SELECT B.BUSINESS_ID, B.BusinessName
FROM BUSINESS B
WHERE StateName = 'CA'
AND B.BusinessName LIKE '%Coffee%';

List all 5-star businesses that have been reviewed by any users between the ages of 15 and
A 5-star business is a business which has an average review rating of 5.

SELECT R.Business_ID, R.Author
FROM Reviews R
WHERE R.Author in (
	SELECT Y.Yelp_ID
	FROM YELP_USER Y
	WHERE (months_between(current_date, Y.DOB)/12) > 15 
	AND (months_between(current_date, Y.DOB)/12) < 25
)
GROUP BY R.Business_ID, R.Author
HAVING AVG(R.Rating) = 5;

List users that have been to at least 3 distinct states. Order by number of states traveled to
(decreasing), break ties with user id (increasing). For each user, list his/her user id, name and
list of states traveled to.

SELECT Y.Yelp_ID, Y.FN, Y.LN, T.StateName
FROM (
	SELECT R.Author as Author, B.StateName as StateName
	FROM REVIEWS R, BUSINESS B 
	WHERE R.Business_ID = B.Business_ID
	AND R.Author in (
		SELECT T.Yelp_User Yelp_User
		FROM
			(SELECT R.Author as Yelp_User, B.StateName as StateName
			FROM REVIEWS R, BUSINESS B 
			WHERE R.Business_ID = B.Business_ID
			GROUP BY R.Author, B.StateName
			) T
		GROUP BY T.Yelp_User
		HAVING COUNT(T.Yelp_User) >= 3
	)
	GROUP BY R.Author, B.StateName
) T, YELP_USER Y
WHERE T.Author = Y.Yelp_ID
ORDER BY (Y.Yelp_ID);