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Node.js - PostgreSQL ORDER BY
3
points
In this article, we would like to show you how to use SQL ORDER BY in Node.js with Postgress.
Note: at the end of this article you can find database preparation SQL queries.
Ascending order:
In this section you can find example that orders results using A-Z
direction.
const { Client } = require('pg');
const client = new Client({
host: '127.0.0.1',
user: 'postgres',
database: 'database_name',
password: 'password',
port: 5432,
});
const fetchUsers = async (orderBy) => {
const query = `SELECT *
FROM "users"
ORDER BY $1`; // it abbreviated form to: ORDER BY $1 ASC
try {
await client.connect(); // creates connection
const { rows } = await client.query(query, [orderBy]); // sends queries
console.log(rows);
} catch (error) {
console.error(error.stack);
} finally {
await client.end(); // closes connection
}
};
fetchUsers('name');
Result:
[
{ id: 2, name: 'Chris', role: 'moderator' },
{ id: 4, name: 'Denis', role: 'moderator' },
{ id: 1, name: 'John', role: 'admin' },
{ id: 3, name: 'Kate', role: 'user' }
]
Descending order:
In this section you can find example that orders results using Z-A
direction.
const { Client } = require('pg');
const client = new Client({
host: '127.0.0.1',
user: 'postgres',
database: 'my_database',
password: 'password',
port: 5432,
});
const fetchUsers = async (orderBy) => {
const query = `SELECT *
FROM "users"
ORDER BY $1 DESC`;
try {
await client.connect(); // gets connection
const { rows } = await client.query(query, [orderBy]); // sends queries
console.log(rows);
} catch (error) {
console.error(error.stack);
} finally {
await client.end(); // closes connection
}
};
fetchUsers('id');
Result:
[
{ id: 4, name: 'Denis', role: 'moderator' },
{ id: 3, name: 'Kate', role: 'user' },
{ id: 2, name: 'Chris', role: 'moderator' },
{ id: 1, name: 'John', role: 'admin' }
]
Database preparation
create_tables.sql
file:
CREATE TABLE "users" (
"id" SERIAL,
"name" VARCHAR(100) NOT NULL,
"role" VARCHAR(15) NOT NULL,
PRIMARY KEY ("id")
);
insert_data.sql
file:
INSERT INTO "users"
("name", "role")
VALUES
('John', 'admin'),
('Chris', 'moderator'),
('Kate', 'user'),
('Denis', 'moderator');