I have two tables. device that can have on blacklisted_device. I would like to get the number of device that include specific user_ids and in the same request number of blacklisted_devices linked.
Here the full sql to try it :
CREATE TABLE device (
device_id serial PRIMARY KEY,
user_id integer,
updated_at timestamp default current_timestamp
);
CREATE TABLE blacklisted_device (
blacklisted_id serial PRIMARY KEY,
device_id integer,
updated_at timestamp default current_timestamp,
CONSTRAINT blacklisted_device_device_id_fkey FOREIGN KEY (device_id)
REFERENCES device (device_id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
);
INSERT INTO device (user_id)
VALUES (1),(2),(2),(7),(88),(99),(102),(106);
INSERT INTO blacklisted_device (device_id)
VALUES (1),(2),(3),(4);
SELECT COUNT(*) AS total_device
FROM device
WHERE user_id IN (7,88,99);
SELECT COUNT(*) AS blacklisted
FROM blacklisted_device
WHERE device_id IN (SELECT device_id FROM device WHERE user_id IN (7,88,99));
As you can see at the end I get the result I want but in two requests. How to get it in one request?
total_device: 3, blacklisted: 1
Feel free to make any comment on all the SQL, I probably made few mistakes.
Thanks
You need a LEFT JOIN:
SELECT COUNT(*) AS total_device,
COUNT(DISTINCT bd.device_id) AS blacklisted
FROM device d
LEFT JOIN blacklisted_device bd
ON d.device_id = bd.device_id
WHERE d.user_id IN (7,88,99);
Related
I think there a few ways to tackle this, but I'm not sure how to do any of them.
I have two tables, the first has ID's and Numbers. The ID's and numbers can potentially be listed more than once, so I create a result table that lists the unique numbers grouped by ID.
My second table has rows (100 million) with the ID and Numbers again. I need to search that table for any ID that has a Number not in the list of Numbers from the result table.
Can redshift do a query based on if the ID matches and the Number exists in the list from the table? Can this all be done in memory/one statement?
DROP TABLE IF EXISTS `myTable`;
CREATE TABLE `myTable` (
`id` mediumint(8) unsigned NOT NULL auto_increment,
`ID` varchar(255),
`Numbers` mediumint default NULL,
PRIMARY KEY (`id`)
) AUTO_INCREMENT=1;
INSERT INTO `myTable` (`ID`,`Numbers`)
VALUES
("CRQ44MPX1SZ",1890),
("UHO21QQY3TW",4370),
("JTQ62CBP6ER",1825),
("RFD95MLC2MI",5014),
("URZ04HGG2YQ",2859),
("CRQ44MPX1SZ",1891),
("UHO21QQY3TW",4371),
("JTQ62CBP6ER",1826),
("RFD95MLC2MI",5015),
("URZ04HGG2YQ",2860),
("CRQ44MPX1SZ",1892),
("UHO21QQY3TW",4372),
("JTQ62CBP6ER",1827),
("RFD95MLC2MI",5016),
("URZ04HGG2YQ",2861);
SELECT ID, listagg(distinct Numbers,',') as Number_List, count(Numbers) as Numbers_Count
FROM myTable
GROUP BY ID
AS result
DROP TABLE IF EXISTS `myTable2`;
CREATE TABLE `myTable2` (
`id` mediumint(8) unsigned NOT NULL auto_increment,
`ID` varchar(255),
`Numbers` mediumint default NULL,
PRIMARY KEY (`id`)
) AUTO_INCREMENT=1;
INSERT INTO `myTable2` (`ID`,`Numbers`)
VALUES
("CRQ44MPX1SZ",1870),
("UHO21QQY3TW",4350),
("JTQ62CBP6ER",1825),
("RFD95MLC2MI",5014),
("URZ04HGG2YQ",2859),
("CRQ44MPX1SZ",1891),
("UHO21QQY3TW",4371),
("JTQ62CBP6ER",1826),
("RFD95MLC2MI",5015),
("URZ04HGG2YQ",2860),
("CRQ44MPX1SZ",1882),
("UHO21QQY3TW",4372),
("JTQ62CBP6ER",1827),
("RFD95MLC2MI",5016),
("URZ04HGG2YQ",2861);
Pseudo Code
Select ID, listagg(distinct Numbers) as Violation
Where Numbers IN NOT IN result.Numbers_List
or possibly: WHERE Numbers NOT LIKE '%' || result.Numbers_List|| '%'
Desired Output
(“CRQ44MPX1SZ”, ”1870,1882”)
(“UHO21QQY3TW”, ”4350”)
EDIT
Going the JOIN route, I am not getting the right results...but I'm pretty sure my WHERE implementation is wrong.
SELECT mytable1.ID, listagg(distinct mytable2.Numbers, ',') as unauth_list, count(mytable2.Numbers) as unauth_count
FROM mytable1
LEFT JOIN mytable2 on mytable1.id = mytable2.id
WHERE (mytable1.id = mytable2.id)
AND (mytable1.Numbers <> mytable2.Numbers)
GROUP BY mytable1.id
Expected output:
(“CRQ44MPX1SZ”, ”1870,1882”, 2)
(“UHO21QQY3TW”, ”4350”, 1)
Just left join the two tables on ID and numbers and check for (where clause) to see if the match wasn't found. Shouldn't be a need for listagg() and complex comparing. Or did I miss part of the question?
I'm new to sql, and I need to write a query for a table that looks like this
CREATE TABLE TESTS
PATH_ID int PRIMARY KEY,
Day DATE NOT NULL,
Direction varchar(255) NOT NULL,
D_ID int NOT NULL,
FOREIGN KEY (D_ID) REFERENCES Drivers(D_ID),
);
INSERT INTO TESTS(PATH_ID,Day,Direction,D_ID)
VALUES (1,'2021-02-01' ,'Right',001),
(2,'2021-02-01' ,'Left',002),
(3,'2021-02-02','Right',002),
What I need to do is write a query that shows drivers (D_ID) who have ONLY ever gone Right (Direction), and show The D_ID, the Day, and all the times the driver went right.
One method is not exists:
select t.*
from tests t
where not exists (select 1
from tests t2
where t2.d_id = t.d_id and t2.direction <> 'Right'
);
you can use not in
select a.* from Tests a where D_ID not in (
select D_ID from Tests where direction <>'Right'
)
I am new in DB and I have a table topics and in this table, I have a foreign key master_topic_id and this foreign key is related to the same table topics column id.
Schema:
CREATE TABLE public.topics (
id bigserial NOT NULL,
created_at timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
published_at timestamp NULL,
master_topic_id int8 NULL,
CONSTRAINT t_pkey PRIMARY KEY (id),
CONSTRAINT t_master_topic_id_fkey FOREIGN KEY (master_topic_id) REFERENCES topics(id
);
I write a query - SELECT * FROM topics WHERE id = 10. But if this record has master_topic_id I need to get data by master_topic_id too.
I tried to do it by using JOIN, but join just concat records, but I need to have data from master_topic_id as new row.
Any help?
I think you are describing:
select t.*
from topics t
where t.id = 10 or
exists (select 1
from topics t2
where t2.master_topic_id = t.id and t2.id = 10
);
However, you might just want:
where 10 in (id, master_topic_id)
Use or in your where condition
SELECT *
FROM topics
WHERE id = 10
or master_topic_id = 10
you can use union all as well
SELECT *
FROM topics
WHERE id = 10
union all
SELECT *
FROM topics
WHERE master_topic_id = 10
I have a problem with making a proper SELECT for my exercise:
There are two tables that I have created:
1. Customer
2. Order
ad. 1
CREATE TABLE public."Customer"
(
id integer NOT NULL DEFAULT nextval('"Customer_id_seq"'::regclass),
name text NOT NULL,
surname text NOT NULL,
address text NOT NULL,
email text NOT NULL,
password text NOT NULL,
CONSTRAINT "Customer_pkey" PRIMARY KEY (id),
CONSTRAINT "Customer_email_key" UNIQUE (email)
)
ad.2
CREATE TABLE public."Order"
(
id integer NOT NULL DEFAULT nextval('"Order_id_seq"'::regclass),
customer_id integer NOT NULL,
item_list text,
order_date date,
execution_date date,
done boolean DEFAULT false,
confirm boolean DEFAULT false,
paid boolean DEFAULT false,
CONSTRAINT "Order_pkey" PRIMARY KEY (id),
CONSTRAINT "Order_customer_id_fkey" FOREIGN KEY (customer_id)
REFERENCES public."Customer" (id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
)
Please do not mind how columns properties were set.
The problem I have is following:
How to make a SELECT query which will give me as a result ids and emails of customers who have ordered something after '2017-09-15'
I suppose that this should go with JOIN but none of the queries I tried have worked :/.
Thanks!
You should post the queries that you tried, but in the meantime try this. It's a simple join :
SELECT DISTINCT id
, email
FROM public."Customer" c
JOIN public."Order" o
ON c.id = o.customer_id
WHERE order_date > '2017-09-15'
In table "Order" you just need to add current constraint for customer id:
customer_id integer REFERENCES Customer (id)
for more information check this page:
https://www.postgresql.org/docs/9.2/static/ddl-constraints.html
So, the query should be like this:
SELECT id, email
FROM Customer
INNER JOIN Order
ON (Order.customer_id = Customer.id)
WHERE order_date >= '2017-09-15'
Also, the useful docs you can check: https://www.postgresql.org/docs/current/static/tutorial-join.html
I am an amateur just trying to finish his last question of his assignment (it is past due at this point, just looking for understanding) I sat and shot attempts at this for almost 5 hours now across two days, and have had no success.
I have tried looking through all the different types of joins, couldn't get grouping to work (ever) and have had little luck with the sorting as well. I can do all of these things one at a time, but the difficulty here was getting all of these things to work in union.
This is the question:
Write a SQL query to retrieve a list that has (source city, source code, destination city,
destination code, and number-of-flights) for all source-dest pairs with at least 2 flights. Order
by the number_of_flights. Note that the “dest”, and “source” attributes in the “flights” table
are both referenced to the “airportid” in the “airports” table.
Here are the tables I have to work with (also came with about 3000 lines of dummy entries)
create table airports (
airportid char(3) primary key,
city varchar(20)
);
create table airlines (
airlineid char(2) primary key,
name varchar(20),
hub char(3) references airports(airportid)
);
create table customers (
customerid char(10) primary key,
name varchar(25),
birthdate date,
frequentflieron char(2) references airlines(airlineid)
);
create table flights (
flightid char(6) primary key,
source char(3) references airports(airportid),
dest char(3) references airports(airportid),
airlineid char(2) references airlines(airlineid),
local_departing_time date,
local_arrival_time date
);
create table flown (
flightid char(6) references flights(flightid),
customerid char(10) references customers,
flightdate date
);
The first problem I ran in to was outputting airports.city twice in the same query but with different results. Not only that, but no matter what I tried when grouping I would always get the same result:
Not a GROUP BY expression
Normally I have fun trying to piece these together, but this has been frustrating. Help!
select source.airportid as source_airportid,
source.city source_city,
dest.airportid as dest_airportid,
dest.city as dest_city,
count(*) as flights
from flights
inner join airports source on source.airportid = flights.source
inner join airports dest on dest.airportid = flights.dest
group by
source.airportid,
source.city,
dest.airportid,
dest.city
having count(*) >= 2
order by 5;
Have you tried a subquery?
SELECT source_airports.city,
source_airports.airportid,
dest_airports.city,
dest_airports.airportid,
x.number_of_flights
FROM
(
SELECT source, dest, COUNT(*) as number_of_flights
FROM flights
GROUP BY source, dest
HAVING COUNT(*) > 1
) as x
INNER JOIN airports as dest_airports
ON dest_airports.airportid = x.dest
INNER JOIN airports as source_airports
ON source_airports.airportid = x.source
ORDER BY x.number_of_flights ASC