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MS SQL Server - find duplicated values in multiple columns
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In this article, we would like to show you how to find duplicated values in multiple columns in MS SQL Server.
Quick solution:
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SELECT 2
[column1], COUNT([column1]),3
[column2], COUNT([column2]),4
[columnN], COUNT([columnN])5
FROM6
[table_name]7
GROUP BY 8
[column1],9
[column2],10
[columnN]11
HAVING 12
(COUNT([column1]) > 1) AND 13
(COUNT([column2]) > 1) AND14
(COUNT([columnN]) > 1);To show how to find duplicated values in multiple columns, 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 duplicated users and countries where:
name_quantity- number of duplicated names,country_quantity- number of duplicated countries.
Note:
This works only when both
nameandcountryin a row are duplicated.
Query:
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SELECT 2
[name], COUNT([name]) AS 'name_quantity',3
[country], COUNT([country]) AS 'country_quantity'4
FROM5
[users]6
GROUP BY 7
[name],8
[country]9
HAVING 10
(COUNT([name]) > 1) AND 11
(COUNT([country]) > 1);Result:
Note:
Notice that
Chrisuser bothname_quantityandcountry_quantityequals2because one user is from a different country.
create_tables.sql file:
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CREATE TABLE [users] (2
[id] INT IDENTITY(1,1),3
[name] VARCHAR(100) NOT NULL,4
[email] VARCHAR(100) NOT NULL,5
[country] VARCHAR(15) NOT NULL,6
PRIMARY KEY ([id])7
);insert_data.sql file:
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INSERT INTO [users]2
([name], [email], [country])3
VALUES4
('Tom', 'tom1@email.com', 'Poland'),5
('Tom', 'tom2@email.com', 'Poland'),6
('Tom', 'tom3@email.com', 'Poland'),7
('Kim', 'kim1@email.com', 'Vietnam'),8
('Kim', 'kim2@email.com', 'Vietnam'),9
('Chris', 'chris1@email.com', 'Spain'),10
('Chris', 'chris2@email.com', 'Spain'),11
('Chris', 'chris3@email.com', 'USA');