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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');
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const connection = mysql.createConnection({ // gets connection with database
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host: 'localhost', // '127.0.0.1'
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user: 'root',
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password: 'password',
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database: 'my_database',
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});
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connection.connect(error => {
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if (error) throw error;
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const query ='SELECT COUNT(*) AS `number of users` FROM `users`';
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connection.query(query, (error, result) => { // sends queries
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connection.end(); // closes connection
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if (error) throw error;
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console.log(result);
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});
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});

Output:
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[ { 'number of users': 8 } ]
create_tables.sql
file:
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CREATE TABLE `users` (
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`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
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`name` VARCHAR(50) NOT NULL,
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`surname` VARCHAR(50) NOT NULL,
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`department_id` INT(10) UNSIGNED,
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`salary` DECIMAL(15,2) NOT NULL,
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PRIMARY KEY (`id`)
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);
insert_data.sql
file:
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INSERT INTO `users`
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( `name`, `surname`, `department_id`, `salary`)
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VALUES
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('John', 'Stewart', 1, '3512.00'),
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('Chris', 'Brown', 2, '1344.00'),
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('Kate', 'Lewis', 3, '6574.00'),
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('Ailisa', 'Gomez', NULL, '6500.00'),
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('Gwendolyn', 'James', 2, '4200.00'),
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('Simon', 'Collins', 4, '3320.00'),
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('Taylor', 'Martin', 2, '1500.00'),
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('Andrew', 'Thompson', NULL, '2100.00');