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MySQL - find duplicated values
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In this article, we would like to show you how to find duplicated values in MySQL.
Quick solution:
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SELECT `column_name`, COUNT(`column_name`)
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FROM `table_name`
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GROUP BY `column_name`
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HAVING COUNT(`column_name`) > 1;
To show how to find duplicated values, we will use the following table:

Note:
At the end of this article you can find database preparation SQL queries.
In this example, we will display the number of names that are duplicated in users
table.
Query:
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SELECT `name`, COUNT(`name`) AS 'name_number'
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FROM `users`
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GROUP BY `name`
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HAVING COUNT(`name`) > 1;
Result:

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(100) NOT NULL,
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`email` VARCHAR(100) NOT NULL,
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`country` VARCHAR(15) NOT NULL,
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PRIMARY KEY (`id`)
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)
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ENGINE=InnoDB;
insert_data.sql
file:
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INSERT INTO `users`
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(`name`, `email`, `country`)
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VALUES
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('Tom', 'tom1@email.com', 'Poland'),
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('Tom', 'tom2@email.com', 'Poland'),
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('Tom', 'tom3@email.com', 'Poland'),
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('Kim', 'kim1@email.com', 'Vietnam'),
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('Kim', 'kim2@email.com', 'Vietnam'),
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('Chris', 'chris1@email.com', 'Spain'),
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('Chris', 'chris2@email.com', 'Spain'),
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('Chris', 'chris3@email.com', 'USA');