Nov 26, 2024 · In this article, we will explain the process of deleting duplicate rows from a SQL table step-by-step, using SQL Server, with examples and outputs. We’ll cover techniques using GROUP BY, CTE, and more, incorporating best practices to help us effectively handle duplicates.

In this article, we explored the process of SQL delete duplicate rows using various ways such as T-SQL, CTE, and SSIS package. You can use the method in which you feel comfortable.

Jul 3, 2017 · To delete duplicate rows in SQL Server where no unique row ID exists, you can use the ROW_NUMBER () function in combination with a common table expression (CTE) to identify and delete the duplicate rows.

Assuming no nulls, you GROUP BY the unique columns, and SELECT the MIN (or MAX) RowId as the row to keep. Then, just delete everything that didn't have a row id: SELECT MIN(RowId) as RowId, Col1, Col2, Col3 . FROM MyTable . GROUP BY Col1, Col2, Col3. MyTable.RowId = KeepRows.RowId. KeepRows.RowId IS NULL.

Jan 10, 2025 · This article provides a script that you can use to remove duplicate rows from a table in Microsoft SQL Server. There are two common methods that you can use to delete …

Sep 18, 2008 · First find the duplicate rows: If there are only few, you can delete them manually: The value of "rowcount" should be n-1 times the number of duplicates. In this example there are 2 dulpicates, therefore rowcount is 1. If you get several duplicate rows, you have to do this for every unique primary key.

Dec 6, 2023 · The most common way to remove duplicate rows from our query results is to use the DISTINCT clause. The simplest way to use this is with the DISTINCT keyword at the start of the SELECT list.

Here’s a guide on how to delete duplicate rows in SQL: Identifying Duplicate Rows. Before deleting duplicate rows, you need to identify them. You can use the GROUP BY clause along with the HAVING clause to find rows where certain columns have duplicate values.

Feb 9, 2025 · Let me share the methods I use most often to clean up duplicate data: 1. The Quick Way: Using ROW_NUMBER () This is my favorite method because it’s clean and efficient: SELECT *, ROW_NUMBER() OVER ( PARTITION BY name, email, phone. ORDER BY id. ) as row_num. FROM customers. 2. The Safe Way: Creating a Clean Table.

Jul 20, 2021 · In SQL Server there are a number of ways to address duplicate records in a table based on the specific circumstances such as: Table with Unique Index – For tables with a unique index, you have the opportunity to use the index to order identify the duplicate data then remove the duplicate records.