Marking rows in an SQL Server table as duplicates

Have you got duplicate rows in your data? Here's how you are can find them and mark them as duplicate.
My SQL Server Udemy courses are:
70-461, 70-761 Querying Microsoft SQL Server with T-SQL: rebrand.ly/que...
98-364: Database Fundamentals (Microsoft SQL Server): rebrand.ly/dat...
70-462 SQL Server Database Administration (DBA): rebrand.ly/sql...
Microsoft SQL Server Reporting Services (SSRS): rebrand.ly/sql...
SQL Server Integration Services (SSIS): rebrand.ly/sql...
SQL Server Analysis Services (SSAS): rebrand.ly/sql...
Microsoft Power Pivot (Excel) and SSAS (Tabular DAX model): rebrand.ly/mic...
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In this video, we will create a new table with two columns - "name" and ID.
We will then find where a "name" has been used for more than once, and then mark them as duplicates.
You can then review them and manipulate them as you want.
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Here is the code for this video:
SELECT *
FROM sys.columns
DROP TABLE IF EXISTS tblColumns
GO
SELECT [name], ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS ID
INTO tblColumns
FROM
sys.columns
WITH myTable AS
(
SELECT *, ROW_NUMBER() OVER(PARTITION BY [name] ORDER BY ID) - 1 AS RowNumbers
FROM tblColumns
)
SELECT *
FROM myTable
WHERE RowNumbers != 0
SELECT *, ROW_NUMBER() OVER(PARTITION BY [name] ORDER BY ID) - 1 AS RowNumbers
FROM tblColumns
ALTER TABLE tblColumns
ADD IsDuplicate INT
UPDATE tblColumns
SET IsDuplicate = ROW_NUMBER() OVER(PARTITION BY [name] ORDER BY ID) - 1
WITH myTable AS
(
SELECT *, ROW_NUMBER() OVER(PARTITION BY [name] ORDER BY ID) - 1 AS RowNumbers
FROM tblColumns
)
UPDATE myTable
SET IsDuplicate = RowNumbers
SELECT * FROM tblColumns
----
Links to my website are:
70-461, 70-761 Querying Microsoft SQL Server with T-SQL: idodata.com/que...
98-364: Database Fundamentals (Microsoft SQL Server): idodata.com/dat...
SQL Server Essential in an Hour: idodata.com/sql...
70-462 SQL Server Database Administration (DBA): idodata.com/sql...
DP-300: Administering Relational Databases: idodata.com/dp-...
Microsoft SQL Server Reporting Services (SSRS): idodata.com/mic...
SQL Server Integration Services (SSIS): idodata.com/sql...
SQL Server Analysis Services (SSAS): idodata.com/sql...
Microsoft Power Pivot (Excel) and SSAS (Tabular DAX model): rebrand.ly/mic...
1Z0-071 Oracle SQL Developer - certified associate: idodata.com/iz0...
SQL for Microsoft Access: idodata.com/sql...
DP-900: Microsoft Azure Data Fundamentals: idodata.com/dp-...

[@qasimawan3568]

You are a brilliant teacher Phillip! Thanks for the video and awesome courses on Udemy!

[@sachovrah]

THX