Quickly delete duplicate records in SQL Server

A few days ago, I read the article in the SQL section of SCID and explained how to quickly delete duplicate records in SQL Server. I browsed it. The author used four methods: creating temporary tables, using cursors, and using unique indexes. After a while, I found that the method I used was the easiest. Good stuff cannot be exclusive...

The data in the test table is as follows:

ProductID	ProductName	Unit	UnitPrice
1	North	Bottole	9.0
2	Chang	Bottole	20.0
2	Chang	Bottole	20.0
3	Anistreed	G	1.0
4	Thu	Kg	2.8
4	Thu	Kg	2.8
4	Thu	Kg	2.8

The records of product Chang and Tofu are repeated in the product information table. To delete these duplicate records, only one of them is retained.

Purpose: To delete duplicate rows in a table. Only one record is left for each Product. Assume that the table name is TEST.

Step 1: add an ID column for the original table.
Alter Table TEST Add Id int Identity (1, 1)
In this way, the table data is processed as follows:

ID	ProductID	ProductName	Unit	UnitPrice
1	1	North	Bottole	9.0
2	2	Chang	Bottole	20.0
3	2	Chang	Bottole	20.0
4	3	Anistreed	G	1.0
5	4	Thu	Kg	2.8
6	4	Thu	Kg	2.8
7	4	Thu	Kg	2.8

Step 2: run the following SQL statement.
Delete from TEST Where ID Not In (Select MIN (ID) From TEST Group by ProdutyID)