Practice Activity - remove duplicate rows in SQL Server (three different ways)

Veröffentlicht am: 07 April 2022
auf dem Kanal: SQL Server 101

12,385

139

Duplicate rows are very annoying. But how can you remove them in SQL Server?
My SQL Server Udemy courses are:
70-461, 70-761 Querying Microsoft SQL Server with T-SQL: https://rebrand.ly/querying-microsoft...
98-364: Database Fundamentals (Microsoft SQL Server): https://rebrand.ly/database-fundamentals
70-462 SQL Server Database Administration (DBA): https://rebrand.ly/sql-server-dba
Microsoft SQL Server Reporting Services (SSRS): https://rebrand.ly/sql-server-ssrs
SQL Server Integration Services (SSIS): https://rebrand.ly/sql-server-ssis
SQL Server Analysis Services (SSAS): https://rebrand.ly/sql-server-ssas-mdx
Microsoft Power Pivot (Excel) and SSAS (Tabular DAX model): https://rebrand.ly/microsoft-powerpiv...
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Duplicate rows may lead to erroneous conclusions, so often you will want them to be deleted. But how can you identify them?
In this video, we'll have a look at three different ways at how we can get rid of them, using DISTINCT, GROUP BY, and UNION - but which is better?

The starting code is:
DROP VIEW IF EXISTS WithDuplicates
GO
CREATE VIEW WithDuplicates AS
SELECT *
FROM sys.objects
UNION ALL
SELECT *
FROM sys.objects
SELECT object_id, [name]
FROM WithDuplicates
ORDER BY object_id

The code that I used in this video is:
SELECT DISTINCT object_id, [name]
FROM WithDuplicates
ORDER BY object_id

SELECT object_id, [name]
FROM WithDuplicates
GROUP BY object_id, [name]
ORDER BY object_id

SELECT object_id, [name]
FROM WithDuplicates
UNION
SELECT object_id, [name]
FROM WithDuplicates
ORDER BY object_id

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