I am making an App where there are message boards and for each board, there is a number of threads and for each thread, there is a number of replies
I need to make a query that gets the threads of a specific board (by board_id) and within each thread, an array of it's replies if no replies for the thread then, get it with an empty replies array
I am not sure if it can be done by a pg query, and it might be achieved by a simple code in the backend modifying the data coming from the query to the format I like but I find a solution currently
here are the tables:
CREATE TABLE threads (
_id SERIAL NOT NULL PRIMARY KEY,
board_id INT NOT NULL REFERENCES board(id),
text VARCHAR(255) NOT NULL,
delete_password VARCHAR(255) NOT NULL,
reported BOOLEAN NOT NULL,
created_on DATE NOT NULL DEFAULT CURRENT_DATE,
bumped_on DATE DEFAULT CURRENT_DATE
);
CREATE TABLE board (
_id SERIAL NOT NULL PRIMARY KEY,
name VARCHAR(255) UNIQUE NOT NULL
);
CREATE TABLE replies (
_id SERIAL PRIMARY KEY NOT NULL,
thread_id INT NOT NULL REFERENCES threads(id),
text VARCHAR(255) NOT NULL,
delete_password VARCHAR(255) NOT NULL,
reported BOOLEAN NOT NULL,
created_on DATE NOT NULL DEFAULT CURRENT_DATE
);
Related
I have a many to many relationship set up with with services and service_categories. Each has a table, and there is a third table to handle to relationship (junction table) called service_service_categories. I have created them like this:
CREATE TABLE services(
service_id SERIAL,
name VARCHAR(255),
summary VARCHAR(255),
profileImage VARCHAR(255),
userAgeGroup VARCHAR(255),
userType TEXT,
additionalNeeds TEXT[],
experience TEXT,
location POINT,
price NUMERIC,
PRIMARY KEY (id),
UNIQUE (name)
);
CREATE TABLE service_categories(
service_category_id SERIAL,
name TEXT,
description VARCHAR(255),
PRIMARY KEY (id),
UNIQUE (name)
);
CREATE TABLE service_service_categories(
service_id INT NOT NULL,
service_category_id INT NOT NULL,
PRIMARY KEY (service_id, service_category_id),
FOREIGN KEY (service_id) REFERENCES services(service_id) ON UPDATE CASCADE,
FOREIGN KEY (service_category_id) REFERENCES service_categories(service_category_id) ON UPDATE CASCADE
);
Now, in my application I would like to add a service_category to a service from a select list for example, at the same time as I create or update a service. In my node js I have this post route set up:
// Create a service
router.post('/', async( req, res) => {
try {
console.log(req.body);
const { name, summary } = req.body;
const newService = await pool.query(
'INSERT INTO services(name,summary) VALUES($1,$2) RETURNING *',
[name, summary]
);
res.json(newService);
} catch (err) {
console.log(err.message);
}
})
How should I change this code to also add a row to the service_service_categories table, when the new service ahas not been created yet, so has no serial number created?
If any one could talk me through the approach for this I would be grateful.
Thanks.
You can do this in the database by adding a trigger to the services table to insert a row into the service_service_categories that fires on row insert. The "NEW" keyword in the trigger function represents the row that was just inserted, so you can access the serial ID value.
https://www.postgresqltutorial.com/postgresql-triggers/
Something like this:
CREATE TRIGGER insert_new_service_trigger
AFTER INSERT
ON services
FOR EACH ROW
EXECUTE PROCEDURE insert_new_service();
Then your trigger function looks something like this (noting that the trigger function needs to be created before the trigger itself):
CREATE OR REPLACE FUNCTION insert_new_service()
RETURNS TRIGGER
LANGUAGE PLPGSQL
AS
$$
BEGIN
-- check to see if service_id has been created
IF NEW.service_id NOT IN (SELECT service_id FROM service_service_categories) THEN
INSERT INTO service_service_categories(service_id)
VALUES(NEW.service_id);
END IF;
RETURN NEW;
END;
$$;
However in your example data structure, it doesn't seem like there's a good way to link the service_categories.service_category_id serial value to this new row - you may need to change it a bit to accommodate
I managed to get it working to a point with multiple inserts and changing the schema a bit on services table. In the service table I added a column: category_id INT:
ALTER TABLE services
ADD COLUMN category_id INT;
Then in my node query I did this and it worked:
const newService = await pool.query(
`
with ins1 AS
(
INSERT INTO services (name,summary,category_id)
VALUES ($1,$2,$3) RETURNING service_id, category_id
),
ins2 AS
(
INSERT INTO service_service_categories (service_id,service_category_id) SELECT service_id, category_id FROM ins1
)
select * from ins1
`,
[name, summary, category_id]
);
Ideally I want to have multiple categories so the category_id column on service table, would become category_ids INT[]. and it would be an array of ids.
How would I put the second insert into a foreach (interger in the array), so it creates a new service_service_categories row for each id in the array?
I would like to know how can I remove all items in table with Prisma2 and Jest ?
I read the CRUD documentation and I try with this :
user.test.js
....
import { PrismaClient } from "#prisma/client"
beforeEach(async () => {
const prisma = new PrismaClient()
await prisma.user.deleteMany({})
})
...
But I have an error :
Invalid `prisma.user.deleteMany()` invocation:
The change you are trying to make would violate the required relation 'PostToUser' between the `Post` and `User` models.
My Database
CREATE TABLE User (
id INTEGER PRIMARY KEY AUTO_INCREMENT NOT NULL,
name VARCHAR(255),
email VARCHAR(255) UNIQUE NOT NULL,
password VARCHAR(255) NOT NULL
);
CREATE TABLE Post (
id INTEGER PRIMARY KEY AUTO_INCREMENT NOT NULL,
title VARCHAR(255) NOT NULL,
createdAt TIMESTAMP NOT NULL DEFAULT now(),
content TEXT,
published BOOLEAN NOT NULL DEFAULT false,
fk_user_id INTEGER NOT NULL,
CONSTRAINT `fk_user_id` FOREIGN KEY (fk_user_id) REFERENCES User(id) ON DELETE CASCADE
);
schema.prisma
model Post {
content String?
createdAt DateTime #default(now())
fk_user_id Int
id Int #default(autoincrement()) #id
published Boolean #default(false)
title String
author User #relation(fields: [fk_user_id], references: [id])
##index([fk_user_id], name: "fk_user_id")
}
model User {
email String #unique
id Int #default(autoincrement()) #id
name String?
password String #default("")
Post Post[]
Profile Profile?
}
You are violating the foreign key constraint between Post and User.
You can not remove a User before deleting its Posts
beforeEach(async () => {
const prisma = new PrismaClient()
await prisma.post.deleteMany({where: {...}}) //delete posts first
await prisma.user.deleteMany({})
})
Or set CASCADE deletion on the foreign key,
this way when you delete a User its posts will be automatically deleted
This is another way to do it, this would remove all rows and its dependant rows, also would reset the ids. This way you can iterate over all the tables and order doesn't matter.
prisma.$executeRaw(`TRUNCATE TABLE ${table} RESTART IDENTITY CASCADE;`)
I'm making a simple multiplayer game using postgres as a database (and node as the BE if that helps). I made the table users which contains all of the user accounts, and a table equipped, which contains all of the equipped items a user has. users has a one -> many relationship with equipped.
I'm running into the situation where I need the data from both tables structured like so:
[
{
user_id: 1,
user_data...
equipped: [
{ user_id: 1, item_data... },
...
],
},
{
user_id: 2,
user_data...
equipped: [
{ user_id: 2, item_data... },
...
],
},
]
Is there a way to get this data in a single query? Is it a good idea to get it in a single query?
EDIT: Here's my schemas
CREATE TABLE IF NOT EXISTS users (
user_id SERIAL PRIMARY KEY,
username VARCHAR(100) UNIQUE NOT NULL,
password VARCHAR(100) NOT NULL,
email VARCHAR(100) NOT NULL,
created_on TIMESTAMP NOT NULL DEFAULT NOW(),
last_login TIMESTAMP,
authenticated BOOLEAN NOT NULL DEFAULT FALSE,
reset_password_hash UUID
);
CREATE TABLE IF NOT EXISTS equipment (
equipment_id SERIAL PRIMARY KEY NOT NULL,
inventory_id INTEGER NOT NULL REFERENCES inventory (inventory_id) ON DELETE CASCADE,
user_id INTEGER NOT NULL REFERENCES users (user_id) ON DELETE CASCADE,
slot equipment_slot NOT NULL,
created_on TIMESTAMP NOT NULL DEFAULT NOW(),
CONSTRAINT only_one_item_per_slot UNIQUE (user_id, slot)
);
Okay so what I was looking for was closer to postgresql json aggregate, but I didn't know what to look for.
Based on my very limited SQL experience, the "classic" way to handle this would just to do a simple JOIN query on the database like so:
SELECT users.username, equipment.slot, equipment.inventory_id
FROM users
LEFT JOIN equipment ON users.user_id = equipment.user_id;
This is nice and simple, but I would need to merge these tables in my server before sending them off.
Thankfully postgres lets you aggregate rows into a JSON array, which is exactly what I needed (thanks #j-spratt). My final* query looks like:
SELECT users.username,
json_agg(json_build_object('slot', equipment.slot, 'inventory_id', equipment.inventory_id))
FROM users
LEFT JOIN equipment ON users.user_id = equipment.user_id
GROUP BY users.username;
Which returns in exactly the format I was looking for.
Here is my model ,
var traders = sequelize.define('traders', {
.....
}, {});
it has many to many self association
traders.belongsToMany(models.traders,{
as:'feedbackClient',
through:'feedback'
});
idea is one trader can give feedback to other trader on each successful trade.
but when i sync it generates table with this SQL query
Executing (default): CREATE TABLE IF NOT EXISTS "feedbacks" ("id" S`ERIAL , "rating" "public"."enum_feedbacks_rating", "comment" VARCHAR(255), "traderId" INTEGER REFERENCES "traders" ("id") ON DELETE CASCADE ON UPDATE CASCADE, "feedbackClientId" INTEGER REFERENCES "traders" ("id") ON DELETE CASCADE ON UPDATE CASCADE, "createdAt" TIMESTAMP WITH TIME ZONE NOT NULL, "updatedAt" TIMESTAMP WITH TIME ZONE NOT NULL, UNIQUE ("traderId", "feedbackClientId"), PRIMARY KEY ("id"));`
how can i remove this constraint?
UNIQUE ("traderId", "feedbackClientId")
so that i can add multiple records with same combination of traderId and feedbackClientId.
Got a solution here, please post your answers if you have better solutions.
This the schema design from my mysql table, I am trying to migrate to mongodb and I am using mongoose , I am confuse of the datatype to use in creating model for my locators table or collection... I am still new on this mongodb hope you can help me. or is it okay in mongoose to use model without declaring datatype ?
like this
var locatorModel = new Schema({});
Thank you in advance.
CREATE TABLE `locators` (
`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
`mch_id` VARCHAR(15) NOT NULL ,
`lat` DOUBLE(10,6) NULL DEFAULT NULL,
`lng` DOUBLE(10,6) NULL DEFAULT NULL,
`latcot` CHAR(1) NULL DEFAULT NULL,
`ttime` TIME NULL DEFAULT NULL,
`tdate` DATE NULL DEFAULT NULL,
`tdatetime` DATETIME NULL DEFAULT NULL,
`velo` DECIMAL(5,2) NULL DEFAULT NULL,
`created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
`updated_at` TIMESTAMP NULL DEFAULT NULL,
PRIMARY KEY (`id`),
INDEX `locators_mch_id_tdatetime_index` (`mch_id`, `tdatetime`),
INDEX `locators_created_at_index` (`created_at`)
)