Delete all by last 10 records...

Question

I have a table where I only want to keep the last 10 records of the of the product.
say for instance, I have a products table and it has apples, oranges... and another table that lists each sales transaction for each product.  As you can see.. you would get 1000's of records in the sales table.
I want to delete all records in the sales table, except for the last 10 records for apples?
any help?

Answer 1

I have a table where I only want to keep the last 10 records of the of the product.
TRUNCATE TABLE is faster than DELETE and uses fewer system and transaction log resources.
Try
-- code #1 v2
IF Object_ID('tempdb..#LastSales','U') is not null DROP TABLE #LastSales;
;with
SalesSeq as (
SELECT *, Seq= row_number() over (partition by IDProd order by SalesDate desc)
  from Sales
SELECT IDSales, IDProd, SalesDate, Qty
  into #LastSales
  from SalesSeq
  where Seq <= 10;
TRUNCATE TABLE Sales;
INSERT into Sales (IDSales, IDProd, SalesDate, Qty)
SELECT IDSales, IDProd, SalesDate, Qty
from #LastSales;
IF Object_ID('tempdb..#LastSales','U') is not null DROP TABLE #LastSales;
You cannot use TRUNCATE TABLE on tables that:
    Are referenced by a FOREIGN KEY constraint
    Participate in an indexed view
    Are published by using transactional replication or merge replication.
To test:
CREATE TABLE Products (IDProd int primary key, DescProd varchar(30));
CREATE TABLE Sales (IDSales int primary key, IDProd int references Products, SalesDate smalldatetime, Qty smallint);
INSERT into Products values
(1, 'apple'), (2, 'orange');
INSERT into Sales values
(1, 1, '20120103', 18), (2, 1, '20120104', 22), (3, 1, '20120105', 50),
(4, 1, '20120105', 19), (5, 2, '20120103', 5), (6, 1, '20120113', 5),
(7, 1, '20120123', 20), (8, 1, '20120203', 7), (9, 1, '20120203', 20),
(10, 1, '20120303', 21), (11, 1, '20120313', 2), (12, 1, '20120401', 15);
José Diz     Belo Horizonte, MG - Brasil