I'm using PostgreSQL
What I need
In SELECT query I need to select owner_type (client or domain). If solution does not exist please help me to rework this schema.
Schema (tables)
Albums - id | client_id (fkey) | domain_id (fkey) | name
Clients - id | first_name | last_name
Domains - id | name
Description: Albums owner can be Client or Domain or future other Nodes...
1. CREATE TABLE QUERY
CREATE TABLE albums
(
id BIGSERIAL PRIMARY KEY,
client_id BIGINT,
domain_id BIGINT,
name VARCHAR(255) NOT NULL,
FOREIGN KEY (client_id) REFERENCES clients(id),
FOREIGN KEY (domain_id) REFERENCES domains(id),
CHECK ((client_id IS NULL) <> (domain_id IS NULL))
);
2. SELECT QUERY
SELECT albums.id,
albums.name,
COALESCE(c.id, d.id) AS owner_id
FROM albums
LEFT JOIN clients c
ON albums.client_id = c.id
LEFT JOIN domains d
ON albums.domain_id = d.id
Need something like -> if c.id === null -> owner_type = 'Domain'
You would seem to want:
SELECT a.id, a.name,
COALESCE(c.id, d.id) AS owner_id,
(CASE WHEN c.id IS NOT NULL THEN 'client' ELSE 'domain' END) as owner_type
FROM albums a LEFT JOIN
clients c
ON a.client_id = c.id LEFT JOIN
domains d
ON a.domain_id = d.id ;
Do you need two separate columns representing client_id and domain_id for the type of owners? It seems that if you were to add more nodes, you would have to add additional columns.
Could you have an owners table representing all types of owners, and have an owner_id foreign key on the albums table?
I was thinking something like this:
CREATE TABLE albums (
id BIGSERIAL PRIMARY KEY,
owner_id BIGINT,
name VARCHAR(255) NOT NULL,
FOREIGN KEY (owner_id) REFERENCES owners(id)
);
CREATE TABLE owners (
id BIGSERIAL PRIMARY KEY,
type VARCHAR(100) NOT NULL,
name VARCHAR(255) NOT NULL
);
You could then query for albums belonging to clients:
SELECT a.id, a.name, o.name AS owner_name
FROM albums a
JOIN owners o ON o.id = a.owner_id
WHERE o.type = 'Client';
As new nodes (types of owners) are added, you simply need to add them to the owners table without modifying the schema of the albums table.
Hope this helps.
Related
I am working on Bus route management system , I made two table first one is Cities and second one is route have following queries
CREATE TABLE Cities
(
ID NUMBER GENERATED ALWAYS AS IDENTITY(START with 1 INCREMENT by 1) PRIMARY KEY,
Name Varchar(30) not null,
)
CREATE TABLE route
(
ID NUMBER GENERATED ALWAYS AS IDENTITY(START with 1 INCREMENT by 1) PRIMARY KEY,
Name Varchar(30) not null,
from NUMBER not null,
to NUMBER NOT NULL,
CONSTRAINT FROM_id_FK FOREIGN KEY(from) REFERENCES Cities(ID),
CONSTRAINT TO_id_FK FOREIGN KEY(to) REFERENCES Cities(ID),
)
i am joining the table through inner join
select CITIES.Name
from CITIES
inner join ROUTES on CITIES.ID=ROUTES.ID
but it show single column as
Name
-----------
but i want result as
from | to
------------------------
what is possible way to do this using inner join
I suspect you need something like the following:
select r.Name, cs.Name SourceCity, cd.Name DestinationCity
from routes r
join cities cs on cs.id = r.from
join cities cd on cd.id = r.to
Hope is working for you
select CITIES.Name,ROUTES.from,ROUTES.to
from CITIES inner join ROUTES on CITIES.ID=ROUTES.ID
I have these Postgres tables:
create table deals_new
(
id bigserial primary key,
slip_id text,
deal_type integer,
timestamp timestamp,
employee_id bigint
constraint employee_id_fk
references common.employees
);
create table twap
(
id bigserial primary key,
deal_id varchar not null,
employee_id bigint
constraint fk_twap__employee_id
references common.employees,
status integer
);
create table employees
(
id bigint primary key,
account_id integer,
first_name varchar(150),
last_name varchar(150)
);
New table to query:
create table accounts
(
id bigint primary key,
account_name varchar(150) not null
);
I use this SQL query:
select d.*, t.id as twap_id
from common.deals_new d
left outer join common.twap t on
t.deal_id = d.slip_id and
d.timestamp between '11-11-2021' AND '11-11-2021' and
d.deal_type in (1, 2) and
d.quote_id is null
where d.employee_id is not null
order by d.timestamp desc, d.id
offset 10
limit 10;
How I can extend this SQL query to search also in table employees by account_id and map the result in table accounts by id? I would like to print also accounts. account_name based on employees .account_id.
You need two joins to to make this work for you. One join to get to the employee table, and one more join to get to the accounts table.
select d.*, t.id as twap_id, a.account_name
from common.deals_new d
left outer join common.twap t on
t.deal_id = d.slip_id and
d.timestamp between '11-11-2021' AND '11-11-2021' and
d.deal_type in (1, 2) and
d.quote_id is null
join employees as e on d.employee_id = e.id
join accounts as a on a.id = e.account_id
where d.employee_id is not null
order by d.timestamp desc, d.id
offset 10
limit 10;
Note: I did not fiddle this one, so could have a typo, but I think you get the idea here.
Let's assume that we have these 2 tables: person and car
CREATE TABLE person (
id BIGSERIAL NOT NULL PRIMARY KEY,
name VARCHAR NOT NULL
);
CREATE TABLE car (
id BIGSERIAL NOT NULL PRIMARY KEY,
make VARCHAR NOT NULL,
person_id BIGINT NOT NULL REFERENCES person(id)
);
What I try to do is to find all people, find every car and create an array of objects like this one
[
{
"id": "PERSON_ID",
"name": "PERSON_NAME",
"cars": [
{
"id": "CAR_ID",
"model": "MODEL_NAME",
"person_id": "PERSON_ID"
}
]
}
]
I have tried using the AS alias with a JOIN on person table from car table but it didn't work. Is there a way to do this? Thank you!
You may try the following. See a working fiddle:
Schema (PostgreSQL v13)
CREATE TABLE person (
id BIGSERIAL NOT NULL PRIMARY KEY,
name VARCHAR NOT NULL
);
CREATE TABLE car (
id BIGSERIAL NOT NULL PRIMARY KEY,
make VARCHAR NOT NULL,
person_id BIGINT NOT NULL REFERENCES person(id)
);
insert into person(name) values ('tom'),('harry');
insert into car (id,make,person_id) values (1,'ford',1),(2,'audi',1),(3,'nissan',2);
Query #1
SELECT
p.id,
p.name,
array_agg(row_to_json(c)) cars
FROM
person p
INNER JOIN
(SELECT id, make model, person_id FROM car) c ON p.id = c.person_id
GROUP BY
p.id,
p.name;
id
name
cars
1
tom
[{"id":1,"model":"ford","person_id":1},{"id":2,"model":"audi","person_id":1}]
2
harry
[{"id":3,"model":"nissan","person_id":2}]
View on DB Fiddle
If you want the result set as an array in Postgres, you can use:
select p.*, array_agg(c)
from person p join
car c
on c.person_id = p.id
group by p.id;
You can do something similar if you want JSON returned as well.
i have the following table structure:
Location----- * Media ----1 Attribute --------* AttributeTranslation
Each Location has n mediaitems attached, containing one optional attribute (text) and n associated translationa for that attribute.
I need to select this data into an array, so that i get for each location the associated medialist for each language.
what i currently do and what i get:
SELECT m.location_id, t.language_id,
array_agg_mult(
ARRAY[ARRAY[m.sortorder::text, m.filename, t.name]] ORDER BY m.sortorder
) as medialist
FROM Media m
LEFT JOIN ATTRIBUTE a ON a.id = m.attribute_id
LEFT JOIN AttributeTranslation t ON a.id = t.attribute_id
WHERE m.location_id = ?
GROUP BY m.location_id, t.language_id
This gives me following result for the given scenario: the current location has 4 images attached, only the first image has an associated attribute containing two translations:
Location_ID Language_ID MEDIALIST
AT_014 1 {{1,'location_image1.jpg','attribute german'}}
AT_014 2 {{1,'location_image1.jpg','attribute english'}}
AT_014 {{2,'location_image2.jpg',null},{3,'location_image3.jpg',null},{4,'location_image4.jpg',null}}
but what i need instead is this:
Location_ID Language_ID MEDIALIST
AT_014 1 {{1,'location_image1.jpg','attribute german'},{2,'location_image2.jpg',null},{3,'location_image3.jpg',null},{4,'location_image4.jpg',null}}
AT_014 2 {{1,'location_image1.jpg','attribute english'},{2,'location_image2.jpg',null},{3,'location_image3.jpg',null},{4,'location_image4.jpg',null}}
those 3 columns are part of a view, so that i can do later:
select * from locationview where location_id = ? and language_id = ?
how can i achieve the desired result here? thanks in advance!
Simplified Table Definitions:
CREATE TABLE LOCATION (
location_id numeric(20) primary key,
description text
);
CREATE TABLE MEDIA (
media_id numeric(20) primary key,
fileName text,
sortorder smallint,
location_id numeric(20) references LOCATION(location_id),
attribute_id numeric(20) references ATTRIBUTE(attribute_id)
);
CREATE TABLE ATTRIBUTE (
attribute_id numeric(20) primary key,
attributetype varchar(100),
);
CREATE TABLE ATTRIBUTETRANSLATION (
translation_id numeric(20),
language_id smallint,
name text,
description text,
attribute_id numeric(20) references ATTRIBUTE(attribute_id)
);
ALTER TABLE ATTRIBUTETRANSLATION add constraint AT_ID primary key(translation_id, language_id)
I am not sure I fully understand your question, but here's an attempt. You could take the output of your query, and match each row that has a language_id with the corresponding rows where language_id is NULL, so that you can then concatenate the medialist arrays. Here's a way to do that by creating an alias of your query with a CTE:
WITH t AS (
SELECT m.location_id, t.language_id,
array_agg(
ARRAY[ARRAY[m.sortorder::text, m.filename, t.name]] ORDER BY m.sortorder
) as medialist
FROM Media m
LEFT JOIN ATTRIBUTE a ON a.attribute_id = m.attribute_id
LEFT JOIN AttributeTranslation t ON a.attribute_id = t.attribute_id
WHERE m.location_id = ?
GROUP BY m.location_id, t.language_id
)
SELECT location_id, t1.language_id, t1.medialist || t2.medialist AS medialist
FROM (SELECT * FROM t WHERE language_id IS NOT NULL) t1
RIGHT OUTER JOIN (SELECT * FROM t WHERE language_id IS NULL) t2 USING (location_id);
I am not sure if this does exactly what you want, but hopefully it will give you some ideas.
I have three tables with the structures outlined below:
CREATE TABLE users (
id BIGSERIAL PRIMARY KEY,
username VARCHAR(255) UNIQUE
);
CREATE TABLE posts (
id BIGSERIAL PRIMARY KEY,
user_id BIGINT REFERENCES users(id) NOT NULL,
category BIGINT REFERENCES categories(id) NOT NULL,
text TEXT NOT NULL
);
CREATE TABLE posts_votes (
user_id BIGINT REFERENCES users(id) NOT NULL,
post_id BIGINT REFERENCES posts(id) NOT NULL
value SMALLINT NOT NULL,
PRIMARY KEY(user_id, post_id)
);
I was able to compose a query that gets each post with its user and its total value using the below query:
SELECT p.id, p.text, u.username, COALESCE(SUM(v.value), 0) AS vote_value
FROM posts p
LEFT JOIN posts_votes v ON p.id=t.post_id
JOIN users u ON p.user_id=u.id
WHERE posts.category=1337
GROUP BY p.id, p.text, u.username
But now I want to also return a column that returns the result of SELECT COALESCE((SELECT value FROM posts_votes WHERE user_id=1234 AND post_id=n), 0) for each post_id n in the above query. What would be the best way to do this?
I think an additional LEFT JOIN is a reasonable approach:
SELECT p.id, p.text, u.username, COALESCE(SUM(v.value), 0) AS vote_value,
COALESCE(pv.value, 0)
FROM posts p JOIN
users u
ON p.user_id=u.id LEFT JOIN
topics_votes v
ON p.id = t.post_id LEFT JOIN
post_votes pv
ON pv.user_id = 1234 AND pv.post_id = p.id
WHERE p.category = 1337
GROUP BY p.id, p.text, u.username, pv.value;