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Node.js - MySQL COUNT()
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In this article, we would like to show you how to use SQL COUNT() function in Node.js.
Note: at the end of this article you can find database preparation SQL queries.
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const mysql = require('mysql');2
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const connection = mysql.createConnection({ // gets connection with database4
host: 'localhost', // '127.0.0.1'5
user: 'root',6
password: 'password',7
database: 'my_database',8
});9
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connection.connect(error => {11
if (error) throw error;12
const query ='SELECT COUNT(*) AS `number of users` FROM `users`';13
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connection.query(query, (error, result) => { // sends queries15
connection.end(); // closes connection16
if (error) throw error;17
console.log(result);18
});19
});
Output:
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[ { 'number of users': 8 } ]create_tables.sql file:
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CREATE TABLE `users` (2
`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,3
`name` VARCHAR(50) NOT NULL,4
`surname` VARCHAR(50) NOT NULL,5
`department_id` INT(10) UNSIGNED,6
`salary` DECIMAL(15,2) NOT NULL,7
PRIMARY KEY (`id`)8
);insert_data.sql file:
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INSERT INTO `users`2
( `name`, `surname`, `department_id`, `salary`)3
VALUES4
('John', 'Stewart', 1, '3512.00'),5
('Chris', 'Brown', 2, '1344.00'),6
('Kate', 'Lewis', 3, '6574.00'),7
('Ailisa', 'Gomez', NULL, '6500.00'),8
('Gwendolyn', 'James', 2, '4200.00'),9
('Simon', 'Collins', 4, '3320.00'),10
('Taylor', 'Martin', 2, '1500.00'),11
('Andrew', 'Thompson', NULL, '2100.00');