I am trying to find:
the total number of doctors which aren't patients
the total number of patients which aren't doctors
the total number of people who are both patients and doctors
I can't seem to get the correct answer.
SQL:
CREATE TABLE persons (
id integer primary key,
name text
);
CREATE TABLE doctors (
id integer primary key,
type text,
FOREIGN KEY (id) REFERENCES persons(id)
);
CREATE TABLE patients (
id integer primary key,
suffering_from text,
FOREIGN KEY (id) REFERENCES persons(id)
);
INSERT INTO persons (id, name) VALUES
(1, 'bob'), (2, 'james'), (3, 'bill'), (4, 'mark'), (5, 'chloe');
INSERT INTO doctors (id, type) VALUES
(2, 'family doctor'), (3, 'eye doctor'), (5, 'family doctor');
INSERT INTO patients (id, suffering_from) VALUES
(1, 'flu'), (2, 'diabetes');
Select statement:
select count(d.id) as total_doctors, count(pa.id) as total_patients, count(d.id) + count(pa.id) as both_doctor_and_patient
from persons p
JOIN doctors d
ON p.id = d.id
JOIN patients pa
ON p.id = pa.id;
http://www.sqlfiddle.com/#!17/98ae9/2
One option uses left joins from persons and conditional aggrgation:
select
count(dr.id) filter(where pa.id is null) cnt_doctor_not_patient,
count(pa.id) filter(where dr.id is null) cnt_patient_not_doctor,
count(pa.id) filter(where do.id is not null) cnt_patient_and_doctor,
count(*) filter(where dr.id is null and pa.id is null) cnt_persons_not_dotor_nor_patient
from persons pe
left join doctors dr on dr.id = pe.id
left join patients pa on pa.id = pe.id
As a bonus, this gives you an opportunity to count the persons that are neither patient nor doctor. If you don't need that information, then a full join is simpler, and does not require bringing the persons table:
select
count(dr.id) filter(where pa.id is null) cnt_doctor_not_patient,
count(pa.id) filter(where dr.id is null) cnt_patient_not_doctor,
count(pa.id) filter(where dr.id is not null) cnt_patient_and_doctor
from doctors dr
full join patients pa using (id)
You can simply solve this using LEFT JOIN like:
--Aren't doctors:
SELECT count(*) from persons as A left join doctors as B on A.id=B.id where B.id is null
--Aren't patients:
SELECT count(*) from persons as A left join patients as B on A.id=B.id where B.id is null
--Both:
SELECT
(SELECT count(*) from persons as A left join patients as B on A.id=B.id where B.id is not null) +
(SELECT count(*) from persons as A left join doctors as B on A.id=B.id where B.id is not null)
AS summ
Here a CTE alternative:
with doc_not_pat
as(
select count(*) as Doc_Not_Pat
from doctors d
where not exists (select 1 from patients p where p.id = d.id)
),
pat_not_doc as(
select count(*) as Pat_Not_Doc
from patients p
where not exists ( select 1 from doctors d where d.id = p.id)
),
pat_and_doc as(
select count(*) as Pat_And_Doc
from patients p
where exists (select 1 from doctors d where d.id = p.id)
)
select (select Doc_Not_Pat
from doc_not_pat dcp) as Doc_Not_Pat,
(select Pat_Not_Doc
from pat_not_doc) as Pat_Not_Doc,
(select Pat_And_Doc
from pat_and_doc) as Pat_And_Doc
Related
I will send the Database Description in an Image.
I tried this Select but I'm afraid that this isn't right
SELECT t.type , a.ICAOId , a.name , ci.id , c.ISOAlpha2ID , p.docReference , ti.docReference , ti.number , p.name , p.surname
FROM dbo.AirportType t
INNER JOIN dbo.Airport a ON t.type = a.type
INNER JOIN dbo.City ci ON a.city = ci.id
INNER JOIN dbo.Country c ON ci.ISOalpha2Id = c.ISOalpha2Id
INNER JOIN dbo.Passenger p ON c.ISOalpha2Id = p.nationality
INNER JOIN dbo.Ticket ti ON p.docReference = ti.docReference
WHERE NOT ci.id = 'Tokyo'
Can you please help to get this right?
enter image description here
You could make a list of the passengers that HAVE flown to the city then use that as a subquery to select the ones not in the list
I am just going to make an example of how it should be done
Subquery:
SELECT p.id FROM passengers
JOIN tickets t ON p.id = t.passengerID
JOIN city c ON c.id = t.cityID
Now you just put that into another query that selects the elements not in it
SELECT * FROM passenger
WHERE id not in (
SELECT p.id FROM passengers
JOIN tickets t ON p.id = t.passengerID
JOIN city c ON c.id = t.cityID
WHERE c.name= 'tokyo'
)
Notice I didn't use your attribute names, you will have to change those.
This was a bit simplified version of what you will have to do because the city is not directly in your tickets table. So you will also have to join tickets, with coupons, and flights to get the people that have flown to a city. But from there it is the same.
Overall I believe this should help you get what you have to do.
A minimal reproducible example is not provided.
Here is a conceptual example, that could be easily extended to a real scenario.
SQL
-- DDL and sample data population, start
DECLARE #passenger TABLE (passengerID INT PRIMARY KEY, passenger_name VARCHAR(20));
INSERT #passenger (passengerID, passenger_name) VALUES
(1, 'Anna'),
(2, 'Paul');
DECLARE #city TABLE (cityID INT PRIMARY KEY, city_name VARCHAR(20));
INSERT #city (cityID, city_name) VALUES
(1, 'Miami'),
(2, 'Orldando'),
(3, 'Tokyo');
-- Already visited cities
DECLARE #passenger_city TABLE (passengerID INT, cityID INT);
INSERT #passenger_city (passengerID, cityID) VALUES
(1, 1),
(2, 3);
-- DDL and sample data population, end
SELECT * FROM #passenger;
SELECT * FROM #city;
SELECT * FROM #passenger_city;
;WITH rs AS
(
SELECT c.passengerID, b.cityID
FROM #passenger AS c
CROSS JOIN #city AS b -- get all possible combinations of passengers and cities
EXCEPT -- filter out already visited cities
SELECT passengerID, cityID FROM #passenger_city
)
SELECT c.*, b.city_name
FROM rs
INNER JOIN #passenger AS c ON c.passengerID = rs.passengerID
INNER JOIN #city AS b ON b.cityID = rs.cityID
ORDER BY c.passenger_name, b.city_name;
Output
passengerID
passenger_name
city_name
1
Anna
Orldando
1
Anna
Tokyo
2
Paul
Miami
2
Paul
Orldando
I want to add the total number of products of the brand to the total column.
http://sqlfiddle.com/#!18/2d00a/1
this my query;
WITH cte AS
(
SELECT id
FROM category
WHERE id = 1
UNION ALL
SELECT c.id
FROM category c, cte
WHERE c.parentid = cte.id
), cte2 AS
(
SELECT brandid, d.catid
FROM products d, cte
WHERE d.catid = cte.id
UNION ALL
SELECT u.brandid, COUNT(DISTINCT u.id)
FROM products u, cte
WHERE catid = cte.id
GROUP BY brandid
)
SELECT DISTINCT
brandid, logo, brand, id, id as total
FROM
brand, cte2
WHERE
id = cte2.brandid
ORDER BY
brand ASC
SELECT b.id,
b.logo,
b.brand,
count(p.id) total
FROM brand b
LEFT JOIN products p ON p.brandid = b.id
GROUP BY b.id, b.logo, b.brand
Assuming you want to filter products based on category 1 (where you include the subcategories as well)
WITH categories_and_subcategories AS (
SELECT id FROM category
WHERE id = 1
UNION ALL
SELECT c.id
FROM category c
INNER JOIN categories_and_subcategories cs
ON c.parentid = cs.id),
filtered_products AS (
SELECT p.id,
p.name,
p.catid,
p.brandid
FROM products p
INNER JOIN categories_and_subcategories c
ON p.catid = c.id
)
SELECT b.id,
b.logo,
b.brand,
count(p.id) total
FROM brand b
LEFT JOIN filtered_products p ON p.brandid = b.id
GROUP BY b.id, b.logo, b.brand
Here is the Query as per my Understanding to get the total products per brand. DBFIDDLE working code
CREATE TABLE brand (
[id] INT
,[brand] VARCHAR(13)
,[logo] VARCHAR(13)
);
INSERT INTO brand ([id], [brand], [logo])
VALUES ('1', 'samsung', 'logo.jpg');
CREATE TABLE products (
[id] INT
,[name] VARCHAR(13)
,[catid] INT
,[brandid] INT
);
INSERT INTO products ([id], [name], [catid], [brandid])
VALUES ('1', 'samsung tv', '2', '1')
,('1', 'samsung2 tv', '2', '1')
SELECT b.Id
,b.brand
,b.logo
,p.Id
,COUNT(1) [total]
FROM brand b
INNER JOIN products p ON b.Id = p.brandId
GROUP BY b.Id
,b.brand
,b.logo
,p.Id
Results:
It's a generic SQL question. I have a query that selects all rows from the Products with extra information from other tables. The problem is that it's EAV scheme and the last relation is somehow reversed and joins break.
The requirements are:
list all Products with Groups
if 'Price' in Values table is available, add this information
explicitly: if 'Price' is not available, there should be Product row without Price information
Products can't be repeated
Additionally: DISTINCT is out of question
I have a working query (below) that uses a subquery to filter values, but I need to get rid of it. I can only uses joins.
SQL Fiddle : http://sqlfiddle.com/#!15/0576b/8
create table Products (
id int primary key,
groupId int,
code varchar(100)
);
create table Groups (
id int primary key,
code varchar(100)
);
create table Values (
id int primary key,
productId int,
typeId int,
value varchar(100)
);
create table ValueTypes (
id int primary key,
name varchar(100)
);
insert into Products values (1, 1, 'P1');
insert into Products values (2, 2, 'P2');
insert into Groups values (1, 'C1');
insert into Groups values (2, 'C2');
insert into Values values (1, 1, 1, 'Aqua');
insert into Values values (2, 1, 2, '$5');
insert into ValueTypes values (1, 'Name');
insert into ValueTypes values (2, 'Price');
My query that works:
SELECT *
FROM Products p
INNER JOIN Groups g ON p.groupId = g.id
LEFT JOIN Values v ON v.productId = p.id AND v.typeId = (SELECT id FROM ValueTypes WHERE name = 'Price')
The question is, how to rewrite it to use joins instead of subquery?
I tried:
SELECT *
FROM Products p
INNER JOIN Groups g ON p.groupId = g.id
LEFT JOIN Values v ON v.productId = p.id
LEFT JOIN ValueTypes vt ON vt.id = v.typeId AND vt.name = 'Price'
But it returns repeated product P1. INNER JOIN on the other hand omits Products without a 'Price' value.
Define JOIN order explicitly
SELECT *
FROM Products p
INNER JOIN Groups g ON p.groupId = g.id
LEFT JOIN ( --product price
SELECT productId, value
FROM Values v2
JOIN ValueTypes vt ON vt.id = v2.typeId AND vt.name = 'Price'
) v ON v.productId = p.id;
EDIT
2 more JOIN versions. Optimizer produces different plan as compared to above version
SELECT *
FROM ValueTypes vt
INNER JOIN Products p ON vt.name = 'Price'
INNER JOIN Groups g ON p.groupId = g.id
LEFT JOIN Values v ON v.productId = p.id AND v.typeId = vt.id;
or slightly different v3
SELECT *
FROM (SELECT id FROM ValueTypes WHERE name = 'Price') vt
CROSS JOIN Products p
INNER JOIN Groups g ON p.groupId = g.id
LEFT JOIN Values v ON v.productId = p.id AND v.typeId = vt.id
You can do as this:
SELECT p.id, p.code, g.id, g.code,
max(case when vt.name='Price'
then v.value
else null end) as price
FROM Products p
LEFT JOIN Groups g ON p.groupId = g.id
LEFT JOIN Values v ON v.productId = p.id
LEFT join ValueTypes vt ON v.typeId = vt.id
group by p.id, p.code, g.id, g.code
See it working here: http://sqlfiddle.com/#!15/0576b/36
I've looked through all the documentation and I'm having an issue putting together this query in Sequel.
select a.*, IFNULL(b.cnt, 0) as cnt FROM a LEFT OUTER JOIN (select a_id, count(*) as cnt from b group by a_id) as b ON b.a_id = a.id ORDER BY cnt
Think of table A as products and table B is a record indicated A was purchased.
So far I have:
A.left_outer_join(B.group_and_count(:a_id), a_id: :id).order(:count)
Essentially I just want to group and count table B, join it with A, but since B does not necessarily have any records for A and I'm ordering it by the number in B, I need to default a value.
DB[:a].
left_outer_join(DB[:b].group_and_count(:a_id).as(:b), :a_id=>:id).
order(:cnt).
select_all(:a).
select_more{IFNULL(:b__cnt, 0).as(:cnt)}
I can help you in MS SQL syntax.
Let's say your tables are Product and Order.
CREATE TABLE Product (
Id INT NOT NULL,
NAME VARCHAR(100) NOT NULL)
CREATE TABLE [Order] (
Id INT NOT NULL,
ProductId INT)
INSERT INTO Product (Id, Name) VALUES
(1, 'Tea'), (2, 'Coffee'), (3, 'Hot Chocolate')
INSERT INTO [Order] (Id, ProductId) VALUES
(1, 1), (2, 1), (3, 1), (4, 2)
This query will give the number of orders each product has, including ones without any orders.
SELECT p.Id AS ProductId,
p.Name AS ProductName,
COUNT(o.Id) AS Orders
FROM Product p
LEFT OUTER JOIN [Order] o
ON p.Id = o.ProductId
GROUP BY
p.Id,
p.Name
ORDER BY
COUNT(o.Id) DESC
I have 3 tables:
(SELECT DISTINCT ID
FROM IDS)a
LEFT OUTER JOIN
(SELECT NAME, ID
FROM NAMES)b
ON a.ID = b.ID
LEFT OUTER JOIN
(SELECT ADDRESS FROM ADDRESSES
WHERE ROWNUM <2
ORDER BY UPDATED_DATE DESC)c
ON a.ID = c.ID
An ID can have only one name but can have multiple addresses. I only want the latest one. This query returns the address as null even when there is an address I guess cause it only fetches the first address from the table and then tries LEFT JOIN it to the ID of addresses which it canno find. What is the correct way of writing this query?
Try KEEP DENSE_RANK
Data source:
CREATE TABLE person
(person_id int primary key, firstname varchar2(4), lastname varchar2(9))
/
INSERT ALL
INTO person (person_id, firstname, lastname)
VALUES (1, 'john', 'lennon')
INTO person (person_id, firstname, lastname)
VALUES (2, 'paul', 'mccartney')
SELECT * FROM dual;
CREATE TABLE address
(person_id int, address_id int primary key, city varchar2(8))
/
INSERT ALL
INTO address (person_id, address_id, city)
VALUES (1, 1, 'new york')
INTO address (person_id, address_id, city)
VALUES (1, 2, 'england')
INTO address (person_id, address_id, city)
VALUES (1, 3, 'japan')
INTO address (person_id, address_id, city)
VALUES (2, 4, 'london')
SELECT * FROM dual;
Query:
select
p.person_id, p.firstname, p.lastname,
x.recent_city
from person p
left join (
select person_id,
min(city) -- can change this to max(city). will work regardless of min/max
-- important you do this to get the recent: keep(dense_rank last)
keep(dense_rank last order by address_id)
as recent_city
from address
group by person_id
) x on x.person_id = p.person_id
Live test: http://www.sqlfiddle.com/#!4/7b1c9/2
Not all database has similar functionality with Oracle's KEEP DENSE_RANK windowing function, you can use plain windowing function instead:
select
p.person_id, p.firstname, p.lastname,
x.recent_city, x.pick_one_only
from person p
left join (
select
person_id,
row_number() over(partition by person_id order by address_id desc) as pick_one_only,
city as recent_city
from address
) x on x.person_id = p.person_id and x.pick_one_only = 1
Live test: http://www.sqlfiddle.com/#!4/7b1c9/48
Or use tuple testing, shall work on databases that doesn't support windowing function:
select
p.person_id, p.firstname, p.lastname,
x.recent_city
from person p
left join (
select
person_id,city as recent_city
from address
where (person_id,address_id) in
(select person_id, max(address_id)
from address
group by person_id)
) x on x.person_id = p.person_id
Live test: http://www.sqlfiddle.com/#!4/7b1c9/21
Not all database supports tuple testing like in the preceding code though. You can use JOIN instead:
select
p.person_id, p.firstname, p.lastname,
x.recent_city
from person p
left join (
select
address.person_id,address.city as recent_city
from address
join
(
select person_id, max(address_id) as recent_id
from address
group by person_id
) r
ON address.person_id = r.person_id
AND address.address_id = r.recent_id
) x on x.person_id = p.person_id
Live test: http://www.sqlfiddle.com/#!4/7b1c9/24
You can use the analytic function RANK
(SELECT DISTINCT ID
FROM IDS) a
LEFT OUTER JOIN
(SELECT NAME, ID
FROM NAMES) b
ON a.ID = b.ID
LEFT OUTER JOIN
(SELECT ADDRESS ,
rank() over (partition by id
order by updated_date desc) rnk
FROM ADDRESSES) c
ON ( a.ID = c.ID
and c.rnk = 1)
Without having access to any database at the moment, you should be able to do
(SELECT DISTINCT ID
FROM IDS) a LEFT OUTER JOIN
(SELECT NAME, ID
FROM NAMES)b ON a.ID = b.ID LEFT OUTER JOIN
(SELECT TOP 1 ADDRESS
FROM ADDRESSES
ORDER BY UPDATED_DATE DESC) c ON a.ID = c.ID
As you might see, the "TOP 1" at 'Address' will only return the first row of the result set.
Also, are you sure that a.ID and c.ID is the same?
I would imagine you need something like .... c ON a.ID = c.AddressID
If not, i'm not entirely sure how you link multiple addresses to a single ID.
(SELECT DISTINCT ID
FROM IDS)a
LEFT OUTER JOIN
(SELECT NAME, ID
FROM NAMES)b
ON a.ID = b.ID
LEFT OUTER JOIN
(SELECT ADDRESS, ROWNUMBER() OVER(PARTITON BY ID ORDER BY UPDATED_DATE DESC) RN
FROM ADDRESSES
)c
ON a.ID = c.ID
where c.RN=1