Related
Tricky to Explain so Ill shrink down the info to a minimum:
But first, I'll try and explain my ultimate goal, I want to take users who trialed a product and determine how that product affected a value as a percentage compared to their average baseline and then average all these percentages with stand devs.
I have database with the a table that has a user_id, a value, a date.
user_id
value
date
int
int
int in epoch miliseconds
I then have a second table which indicates when a trial began and ends for a user and the product they are using for said trial.
user_id
start_date
end_date
product id
int
int in epoch milisecs
int in epoch milisecs
int
What I want to do is gather all the user's trials for one product type, and for each user that participated get a baseline value and their percent change each day. Then take all these percentages and average them and get a standard deviation for each day.
One problem is date needs to convert to days since start_date so anything between the start date and the first 24 hrs will be lumped as day 0, next 24 as day 1, and so forth. So ill be averaging the percents of each day
Not every day was recorded for each user so some will have multiple missing days, so I cant need to mark each day as days from start
The start_date's are random between users
So the graph will look like this:
picture
I would prefer to do as much of it in sql as possible, but the rest will be in Golang.
I was thinking about grabbing each trial , and then each trial will have an array of results. so then I iterate over each trial and iteriate over the results for each trial picking day 0, day 1, day 2 and saving these in their own arrays which I will then average. Everything start getting super messy though
such as in semi pseudo code:
db.Query("select user_id, start_date from trials where product_id = $1", productId).Scan(&trial.UserId, &trial.StartDate)
//extract trials from rows
for _, trial := range trials {
// extract leadingAvgStart from StartDate
db.QueryRow("select AVG(value) from results where user_id = $1 date between $2 and $3", trial.UserId, leadingAvgStart, trial.StartDate)
// Now we have the baseline for the user
rows := db.Query("select value, date from results where product_id = $1", start)
//Now we extract the results and have and array
//Convert Dates to Dates from start Date
//...? It just start getting ugly and I believe there has to be a better way
}
How can I do most of the heavy lifting with sql?
create table users (id int PRIMARY KEY, name text);
create table products (id int PRIMARY KEY, name text);
create table values (
id int PRIMARY KEY
, user_id int REFERENCES users(id)
, value int
, date numeric
);
create table trials (
id int PRIMARY KEY
, user_id int REFERENCES users(id)
, start_date numeric
, end_date numeric
, product_id int REFERENCES products(id)
);
INSERT INTO users (id, name ) VALUES
(1,'John'),
(2,'Jane'),
(3,'Billy'),
(4,'Miranda');
INSERT INTO products (id, name ) VALUES
(1, 'pill A'),
(2, 'pill B'),
(3, 'pill C'),
(4, 'exercise bal'),
(5, 'diet plan');
INSERT INTO trials (id,user_id,start_date,end_date,product_id) VALUES
(1, 1, 1667896408000, 1668099442000, 1),
(2, 1, 1667896408000, 1668099442000, 2),
(3, 2, 1667576960000, 1668074401000, 3),
(4, 3, 1667896408000, 1668099442000, 1);
INSERT INTO values (id, user_id, value, date) VALUES
(38, 1, 7, 1668182428000),
(1, 1, 7, 1668099442000),
(2, 1, 8, 1668074401000),
(3, 1, 8, 1668012300000),
(4, 1, 6, 1668011197000),
(5, 1, 6, 1667978268000),
(6, 1, 9, 1667925002000),
(7, 1, 9, 1667896408000),
(8, 1, 4, 1667838601000),
(9, 1, 6, 1667803049000),
(10, 1, 7, 1667576960000),
(12, 1, 5, 1667546428000),
(13, 1, 8, 1667490149000),
(14, 2, 8, 1668182428000),
(15, 2, 7, 1668099442000),
(16, 2, 8, 1668074401000),
(17, 2, 9, 1668012300000),
(18, 2, 6, 1668011197000),
(19, 2, 6, 1667978268000),
(20, 2, 5, 1667925002000),
(21, 2, 9, 1667896408000),
(22, 2, 4, 1667803049000),
(23, 2, 4, 1667576960000),
(24, 2, 5, 1667546428000),
(25, 2, 9, 1667490149000),
(26, 3, 6, 1668182428000),
(27, 3, 7, 1668099442000),
(28, 3, 8, 1668074401000),
(29, 3, 9, 1668011197000),
(30, 3, 6, 1667978268000),
(31, 3, 9, 1667925002000),
(32, 3, 9, 1667896408000),
(33, 3, 8, 1667838601000),
(34, 3, 6, 1667803049000),
(35, 3, 4, 1667576960000),
(36, 3, 5, 1667546428000),
(37, 3, 6, 1667490149000);
Ok I figures it out, basically I do two inner join queries and treat those as tables and then inner join those, and use a group by to average
select
query1.product_uuid,
query1.days,
AVG(query1.value / query2.avg) as avg_percent
from
(
select
DATE_PART(
'day',
to_timestamp(
values
.date / 1000
):: date - trials.start_date
) as days,
trials.uuid as trial_uuid,
trials.product_uuid,
values
.value as value
from
values
as
values
inner join product_trials as trials ON
values
.user_id = trials.user_id
where
values
.source = 'Trued'
and
values
.use = 'true'
AND trials.start_date IS NOT NULL
AND trials.end_date IS NOT NULL
AND to_timestamp(
values
.date / 1000
):: date > trials.start_date
AND to_timestamp(
values
.date / 1000
):: date < trials.end_date
) as query1
inner join (
select
values
.user_id,
trials.uuid as trial_uuid,
AVG(value)
from
values
inner join product_trials as trials ON
values
.user_id = trials.user_id
where
source = 'Trued'
and use = true
AND trials.start_date IS NOT NULL
AND trials.end_date IS NOT NULL
AND to_timestamp(
values
.date / 1000
):: date < trials.start_date
AND DATE_PART(
'day',
to_timestamp(
values
.date / 1000
):: date - trials.start_date
) > -20
GROUP BY
values
.user_id,
trials.uuid
) as query2 ON query1.trial_uuid = query2.trial_uuid
where
query2.avg > 0
GROUP BY
query1.days,
query1.product_uuid
ORDER BY
query1.product_uuid,
query1.days
I attempted to do it using the analytical function, but it appears that I did so improperly...
How can I receive the output from the table I've been given?
CREATE TABLE rides (
ride_id INT,
driver_id INT,
ride_in_kms INT,
ride_fare FLOAT,
ride_date DATE
);
INSERT INTO rides VALUES (1, 1, 3, 4.45, "2016-05-16");
INSERT INTO rides VALUES (2, 1, 4, 8.46, "2016-05-16");
INSERT INTO rides VALUES (3, 2, 6, 11.9, "2016-05-16");
INSERT INTO rides VALUES (4, 3, 3, 6.76, "2016-05-16");
INSERT INTO rides VALUES (5, 2, 6, 13.55, "2016-05-16");
INSERT INTO rides VALUES (6, 4, 3, 4.91, "2016-05-20");
INSERT INTO rides VALUES (7, 1, 7, 16.77, "2016-05-20");
INSERT INTO rides VALUES (8, 3, 9, 16.18, "2016-05-20");
INSERT INTO rides VALUES (9, 2, 3, 6.07, "2016-05-20");
INSERT INTO rides VALUES (10, 4, 4, 6.25, "2016-05-20");
Output result
Thanks in advance
The general gist is to use an expression within the sum() to operate on the correct rows:
select
driver_id,
sum(case when ride_date = "2016-05-16" then ride_in_kms else 0 end) `KMS_MAY_16`,
sum(case when ride_date = "2016-05-20" then ride_in_kms else 0 end) `KMS_MAY_20`
from
group by driver_id;
The particular syntax available, and how to express the column label depends on what database you are using.
How can I improve this query for use in large tables....?
I use a table ('DataValues') to store a collection of values ('Value') for collections ('Visit_id') ie it records certain values for each visit.
I use a table ('MatchItems') to store dynamic match sets 'MatchSet' of values ('Value'), sets can contain any number of values. The table also has a IsNeg field to indicate if the match should require a value to be not present in the visit collection.
This allows me to dynamically match visits that conform to certain criteria such as
Must contain values A, B and C and NOT D OR C and B AND NOT A.
ie (Value = A and Value = B and Value = C and Value /= D)
or (Value = C and Value = B and Value /= A)
I have a query that delivers a reasonable solution fiddle:
CREATE TABLE DataValues (
id NUMBER(5) CONSTRAINT DataValues_pk PRIMARY KEY,
Visit_id Number(5) ,
Value varchar(5)
);
INSERT INTO DataValues VALUES (1, 1, 'M');
INSERT INTO DataValues VALUES (2, 1, 'I');
INSERT INTO DataValues VALUES (3, 1, 'C');
INSERT INTO DataValues VALUES (4, 1, 'K');
INSERT INTO DataValues VALUES (5, 1, 'E');
INSERT INTO DataValues VALUES (6, 1, 'Y');
INSERT INTO DataValues VALUES (7, 2, 'M');
INSERT INTO DataValues VALUES (8, 2, 'O');
INSERT INTO DataValues VALUES (9, 2, 'U');
INSERT INTO DataValues VALUES (10, 2, 'S');
INSERT INTO DataValues VALUES (11, 2, 'E');
INSERT INTO DataValues VALUES (12, 3, 'C');
INSERT INTO DataValues VALUES (13, 3, 'A');
INSERT INTO DataValues VALUES (14, 3, 'T');
INSERT INTO DataValues VALUES (15, 4, 'S');
INSERT INTO DataValues VALUES (16, 4, 'A');
INSERT INTO DataValues VALUES (17, 4, 'T');
INSERT INTO DataValues VALUES (18, 5, 'M');
INSERT INTO DataValues VALUES (19, 5, 'A');
INSERT INTO DataValues VALUES (20, 5, 'T');
CREATE TABLE MatchItems (
id NUMBER(5) CONSTRAINT MatchItems_pk PRIMARY KEY,
MatchSet Number(5),
Value VARCHAR(5),
IsNeg NUMBER(1) NOT NULL CHECK (IsNeg in (0,1))
);
INSERT INTO MatchItems VALUES (1, 1, 'M', 0);
INSERT INTO MatchItems VALUES (2, 1, 'I', 0);
INSERT INTO MatchItems VALUES (3, 1, 'C', 0);
INSERT INTO MatchItems VALUES (4, 1, 'K', 0);
INSERT INTO MatchItems VALUES (5, 1, 'E', 0);
INSERT INTO MatchItems VALUES (6, 1, 'Y', 0);
INSERT INTO MatchItems VALUES (7, 2, 'C', 0);
INSERT INTO MatchItems VALUES (8, 2, 'A', 0);
INSERT INTO MatchItems VALUES (9, 3, 'A', 0);
INSERT INTO MatchItems VALUES (10, 3, 'T', 0);
INSERT INTO MatchItems VALUES (11, 4, 'S', 1);
INSERT INTO MatchItems VALUES (12, 4, 'A', 0);
INSERT INTO MatchItems VALUES (13, 4, 'K', 1);
INSERT INTO MatchItems VALUES (14, 5, 'A', 0);
INSERT INTO MatchItems VALUES (15, 5, 'T', 0);
SELECT
MatchItems.MatchSet,
DataValues.Visit_id,
GpMatchItems.Count TgtCount,
Count(MatchItems.Id),
sum(MatchItems.IsNeg)
FROM DataValues
LEFT JOIN MatchItems ON MatchItems.Value = DataValues.Value
--AND MatchItems.MatchSet = 4
LEFT JOIN (SELECT
MatchItems.MatchSet,
count(*) Count
FROM MatchItems
WHERE
MatchItems.IsNeg = 0
GROUP BY
MatchItems.MatchSet) GpMatchItems ON GpMatchItems.MatchSet = MatchItems.MatchSet
HAVING
Count(MatchItems.Id) = GpMatchItems.Count
AND sum(MatchItems.IsNeg) = 0
GROUP BY
MatchItems.MatchSet,
DataValues.Visit_id,
GpMatchItems.Count
How can I improve the performance of this query where the DataValues table contains 100m records, and MatchItems may include a collection of 50 sets each of 2 - 20 values?
You can try this version using Analytic functions and see if it performs any better. This query removes the subquery GpMatchItems that you are joining with.
SELECT DISTINCT matchset,
visit_id,
tgtcount,
match_visit_count,
isneg_sum
FROM (SELECT MatchItems.MatchSet,
DataValues.Visit_id,
COUNT (DISTINCT CASE MatchItems.IsNeg WHEN 0 THEN MatchItems.id ELSE NULL END)
OVER (PARTITION BY MatchItems.MatchSet)
AS tgtcount,
COUNT (*) OVER (PARTITION BY MatchItems.MatchSet, DataValues.Visit_id)
AS match_visit_count,
SUM (MatchItems.IsNeg) OVER (PARTITION BY MatchItems.MatchSet, DataValues.Visit_id)
AS isneg_sum
FROM DataValues LEFT JOIN MatchItems ON MatchItems.VALUE = DataValues.VALUE)
WHERE tgtcount = match_visit_count AND isneg_sum = 0;
I have adjusted EJ's suggestion to include a LEFT JOIN to collect the tgtCount to identify the total number of good matches required in each MatchSet:
SELECT DISTINCT matchset,
visit_id,
tgtcount,
match_visit_count,
isneg_sum
GpMatchItems.count tgtCount
FROM
COUNT (*) OVER (PARTITION BY MatchItems.MatchSet, DataValues.Visit_id)
AS match_visit_count,
SUM (MatchItems.IsNeg) OVER (PARTITION BY MatchItems.MatchSet, DataValues.Visit_id)
AS isneg_sum
FROM DataValues
LEFT JOIN MatchItems ON MatchItems.VALUE = DataValues.VALUE)
LEFT JOIN ( SELECT
MatchItems.MatchSet,
count(*) Count
FROM MatchItems
WHERE MatchItems.IsNeg = 0
GROUP BY
MatchItems.MatchSet) GpMatchItems
ON GpMatchItems.MatchSet = MatchItems.MatchSet
)
WHERE
tgtcount = match_visit_count
AND isneg_sum = 0;
Good evening everyone,
I'm working on a assignment and can't figure out the following, I have two tables:
CREATE TABLE Rental (
rental_id DECIMAL(12) PRIMARY KEY,
customer_id DECIMAL(12),
movie_id DECIMAL(12),
delivery_status VARCHAR(64),
return_status VARCHAR(64));
and
CREATE TABLE Movie (
movie_id DECIMAL(12) PRIMARY KEY,
DVD_id INTEGER NOT NULL,
title VARCHAR(64) NOT NULL,
stock_number DECIMAL(12),
director_id DECIMAL(12),
genre_id DECIMAL(12),
release_date DATE NOT NULL,
restrictions VARCHAR(256) NOT NULL);
I need to do the following, list the names of all movies that are currently unavailable, rented and not yet returned. And this is my query:
SELECT Movie.movie_id, Movie.title, Movie.stock_number
FROM Movie
WHERE (Movie.movie_id, Movie.stock_number) NOT IN (
SELECT Rental.movie_id,
COUNT(Rental.return_status) AS number_of_unreturned
FROM Rental
WHERE Rental.return_status = 'Unreturned'
GROUP BY Rental.movie_id
HAVING COUNT (Rental.return_status) > 1) AND Movie.stock_number = 0;
I definitely have movies in Movie table that are not "Unreturend" but I get no rows selected all the time. Any advices or directions to think would be appreciated. Thanks!
I edited this post and added the content of the tables.
INSERT INTO Movie VALUES (1, 1, 'Amblin', 1, 1, 1, CAST('18-Dec-1968' AS DATE), 'G');
INSERT INTO Movie VALUES (2, 2, 'Duel', 2, 1, 2, CAST('13-Nov-1971' AS DATE), 'R');
INSERT INTO Movie VALUES (3, 3, 'Something Evil ', 3, 1, 3, CAST('21-Jan-1972' AS DATE), 'R');
INSERT INTO Movie VALUES (4, 4, 'The Sugarland Express ', 4, 1, 4, CAST('05-Apr-1974' AS DATE), 'PG13');
INSERT INTO Movie VALUES (5, 5, 'Jaws', 5, 1, 3, CAST('20-Jun-1975' AS DATE), 'R');
INSERT INTO Movie VALUES (6, 6, 'Close Encounters of the Third Kind', 6, 1, 5, CAST('16-Nov-1977' AS DATE), 'PG13');
INSERT INTO Movie VALUES (7, 7, ' 1941', 7, 1, 6, CAST('14-Dec-1979' AS DATE), 'G');
INSERT INTO Movie VALUES (8, 8, 'Raiders of the Lost Ark', 8, 1, 7, CAST('12-Jun-1981' AS DATE), 'PG13');
INSERT INTO Movie VALUES (9, 9, 'E.T. the Extra-Terrestrial', 9, 1, 5, CAST('11-Jun-1982' AS DATE), 'PG13');
INSERT INTO Movie VALUES (10, 10, 'Twilight Zone: The Movie', 10, 1, 3, CAST('24-Jun-1983' AS DATE), 'R');
INSERT INTO Movie VALUES (11, 11, 'Indiana Jones and the Temple of Doom', 11, 1, 7, CAST('23-May-1984' AS DATE), 'PG13');
INSERT INTO Movie VALUES (12, 12, 'The Color Purple', 12, 1, 4, CAST('18-Dec-1985' AS DATE), 'G');
INSERT INTO Movie VALUES (13, 13, 'Empire of the Sun', 13, 1, 4, CAST('25-Dec-1987' AS DATE), 'G');
INSERT INTO Movie VALUES (14, 14, 'Always', 14, 1, 4, CAST('22-Dec-1989' AS DATE), 'G');
INSERT INTO Movie VALUES (15, 15, 'Indiana Jones and the Last Crusade', 15, 1, 7, CAST('24-May-1989' AS DATE), 'G');
INSERT INTO Movie VALUES (16, 16, 'Hook', 16, 1, 8, CAST('11-Dec-1991' AS DATE), 'G');
INSERT INTO Movie VALUES (17, 17, 'Jurassic Park ', 17, 1, 5, CAST('11-Jun-1993' AS DATE), 'PG13');
INSERT INTO Movie VALUES (18, 18, 'Schindler''s List', 18, 1, 4, CAST('15-Dec-1993' AS DATE), 'PG13');
INSERT INTO Movie VALUES (19, 19, 'The Lost World: Jurassic Park', 19, 1, 5, CAST('23-May-1997' AS DATE), 'PG13');
INSERT INTO Movie VALUES (20, 20, 'Amistad', 20, 1, 4, CAST('10-Dec-1997' AS DATE), 'PG13');
INSERT INTO Movie VALUES (21, 21, 'Saving Private Ryan', 21, 1, 4, CAST('24-Jul-1998' AS DATE), 'PG13');
INSERT INTO Movie VALUES (22, 22, 'A.I. Artificial Intelligence', 22, 1, 4, CAST('29-Jun-2001' AS DATE), 'PG13');
INSERT INTO Movie VALUES (23, 23, 'Minority Report', 23, 1, 7, CAST('21-Jun-2002' AS DATE), 'PG13');
INSERT INTO Movie VALUES (24, 24, 'Catch Me If You Can', 24, 1, 8, CAST('25-Dec-2002' AS DATE), 'PG13');
INSERT INTO Movie VALUES (25, 25, ' The Terminal', 25, 1, 4, CAST('18-Jun-2004' AS DATE), 'G');
INSERT INTO Movie VALUES (26, 26, 'War of the Worlds', 26, 1, 5, CAST('29-Jun-2005' AS DATE), 'PG13');
INSERT INTO Movie VALUES (27, 27, 'Munich', 27, 1, 4, CAST('23-Dec-2005' AS DATE), 'PG13');
INSERT INTO Movie VALUES (28, 28, 'Indiana Jones and the Kingdom of the Crystal Skull', 28, 1, 7, CAST('22-May-2008' AS DATE), 'PG13');
INSERT INTO Movie VALUES (29, 29, 'The Adventures of Tintin', 28, 1, 7, CAST('21-Dec-2011' AS DATE), 'PG13');
INSERT INTO Movie VALUES (30, 30, 'War Horse', 30, 1, 4, CAST('25-Dec-2011' AS DATE), 'PG13');
INSERT INTO Movie VALUES (31, 31, 'Lincoln', 31, 1, 4, CAST('09-Nov-2012' AS DATE), 'PG13');
INSERT INTO Movie VALUES (32, 32, 'Bridge of Spies', 32, 1, 4, CAST('16-Oct-2015' AS DATE), 'PG13');
INSERT INTO Movie VALUES (33, 33, 'The BFG', 33, 1, 8, CAST('01-Jul-2016' AS DATE), 'PG13');
INSERT INTO Movie VALUES (34, 34, 'Praying with Anger', 34, 2, 5, CAST('12-Sep-1992' AS DATE), 'PG13');
INSERT INTO Movie VALUES (35, 35, 'Wide Awake', 35, 2, 4, CAST('20-Mar-1998' AS DATE), 'G');
INSERT INTO Movie VALUES (36, 36, 'The Sixth Sense', 36, 2, 2, CAST('06-Aug-1999' AS DATE), 'PG13');
INSERT INTO Movie VALUES (37, 37, 'Unbreakable', 37, 2, 2, CAST('22-Nov-2000' AS DATE), 'PG13');
INSERT INTO Movie VALUES (38, 38, 'Signs', 38, 2, 2, CAST('02-Aug-2002' AS DATE), 'PG13');
INSERT INTO Movie VALUES (39, 39, 'The Village', 39, 2, 2, CAST('30-Jul-2004' AS DATE), 'PG13');
INSERT INTO Movie VALUES (40, 40, 'Lady in the Water', 40, 2, 8, CAST('21-Jul-2006' AS DATE), 'PG13');
INSERT INTO Movie VALUES (41, 41, 'The Happening', 41, 2, 2, CAST('13-Jun-2008' AS DATE), 'R');
INSERT INTO Movie VALUES (42, 42, 'The Last Airbender', 42, 2, 7, CAST('02-Jul-2010' AS DATE), 'G');
INSERT INTO Movie VALUES (43, 43, 'After Earth', 43, 2, 7, CAST('31-May-2013' AS DATE), 'G');
INSERT INTO Movie VALUES (44, 44, 'The Visit', 44, 2, 3, CAST('11-Sep-2015' AS DATE), 'R');
INSERT INTO Movie VALUES (45, 45, 'Split', 45, 2, 2, CAST('20-Jan-2017' AS DATE), 'PG13');
and
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 1, 1, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 2, 1, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 3, 6, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 4, 7, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 2, 2, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 2, 37, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 5, 1, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 5, 24, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 5, 3, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 6, 13, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 6, 2, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 6, 8, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 6, 1, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 5, 2, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 5, 3, 'Delivered', 'Unreturned');
INSERT INTO Rental VALUES (sequence_rental.NEXTVAL, 3, 27, 'Delivered', 'Returned');
Sorry if that is a too long post.
I don't want to write the code since you are a student. I'll give some direction though. In your where clause you're comparing (movie.movie_id = rental.movie_id) and (movie.stock_number = count(rental.return_status). Comparing the stock_number to the count of returns is incorrect.
When returning columns from multiple tables, use a join. The in statement does a comparison. Count is not being returned.
Join movies and the "in" subquery on movie_id. Create an alias on the subquery so you can join it.
Add the count column to the topmost outer select
Please try, if this logic is correct, I did not quite understand column naming. You might change last row (having) to correct it.
SELECT
m.movie_id, m.title, m.stock_number -- Getting movie id, movie title, stock number
FROM Movie m -- from movie table
JOIN rental r
ON (m.movie_id = r.movie_id) -- joining rental table in movie_id
WHERE
r.return_status = 'Unreturned' -- where return_status is unreturned
GROUP BY
m.movie_id, m.title, m.stock_number -- grouping_by (same as select)
HAVING
SUM(r.movie_id) > m.stock_number; -- restricting group by quantity
To resolve the query try first to break it down in the components you need.
In this case you need to compare the number of rented movies against the stock of movies.
So write 2 separte queries:
1 - One that will provide the movie id and the number to movies in stock.
2 - Another for the movie id and the number of rentals. For this one you have to count the unretured.
After you have the two queries, you can use them as subqueries of a higer level query that treats each or these queries as a table joined by the common id field.
And add awhere clause comparing the stock with the counted field.
Example:
Table A: id, name, age
Table B: table_b_id, table_a_id, telephone, address
Query 1: select id, name, age from A
Query 2: select table_a_id, telephone, address from B
select Q1.id, Q1.name, Q1.age, Q2telephone, Q2.address
from
(select A.id, A.name, A.age from A) Q1,
(select B.table_a_id, B.telephone, B.address from B) Q2
where
Q1.id = Q2.table_a_id
I have this Data in DB
CREATE TABLE Stu_Table
(
Stu_Id VARCHAR(2),
Stu_Name VARCHAR(15),
Stu_Class VARCHAR(10),
sub_id VARCHAR(2),
marks VARCHAR(3)
);
INSERT INTO Stu_Table VALUES (1, 'Komal', 10, 1, 45);
INSERT INTO Stu_Table VALUES (2, 'Ajay', 10, 1, 56);
INSERT INTO Stu_Table VALUES (3, 'Rakesh', 10, 1, 67);
INSERT INTO Stu_Table VALUES (1, 'Komal', 10, 2, 47);
INSERT INTO Stu_Table VALUES (2, 'Ajay', 10, 2, 53);
INSERT INTO Stu_Table VALUES (3, 'Rakesh', 10, 2, 57);
INSERT INTO Stu_Table VALUES (1, 'Komal', 10, 3, 45);
INSERT INTO Stu_Table VALUES (2, 'Ajay', 10, 3, 56);
INSERT INTO Stu_Table VALUES (3, 'Rakesh', 10, 3, 67);
INSERT INTO Stu_Table VALUES (1, 'Komal', 10, 4, 65);
INSERT INTO Stu_Table VALUES (2, 'Ajay', 10, 4, 56);
INSERT INTO Stu_Table VALUES (3, 'Rakesh', 10, 4, 37);
INSERT INTO Stu_Table VALUES (1, 'Komal', 10, 5, 65);
INSERT INTO Stu_Table VALUES (2, 'Ajay', 10, 5, 46);
INSERT INTO Stu_Table VALUES (3, 'Rakesh', 10, 5, 63);
And I'm doing this query on this data.
SELECT *
FROM
(
SELECT
Stu_Id,
MIN(marks) AS mini,
AVG(marks) AS per
FROM stu_table
GROUP BY stu_id
HAVING MIN(marks) > 45
);
And I'm getting this:
Stu_Id| mini | per
1 | 45 | 53.4
2 | 46 | 53.4
3 | 37 | 58.2
I don't understand why I still see Stu_Id 1 with min(mark)=45 when I clearly have this HAVING min(marks)>45 in my query.
Runnable Demo
FIX:
Thanks to #sybkar and #Martin Smith!
I set the marks type as a string.
It's should be INT...
Thanks guys!
Working perfect!
create table Stu_Table(Stu_Id INT(2), Stu_Name varchar(15),
Stu_Class varchar(10),sub_id INT(2),marks INT(3));<--INT!!!
I don't understand why I still see Stu_Id 1 with min(mark)=45
when I clearly have this HAVING min(marks)>45 in my query.
You don't. Or at the least the demo you have provided doesn't.
In general any weird results that you are getting will be because marks is being stored as a string so MIN(marks) will be bringing back the earliest in alphabetical order though.
For example HAVING MIN(marks) > 45 will also bring back 5, 6, 7, 8 and 9