I have two tables in the database: Product and ProductVersion , each product can have n ProductVersions. ProductVersion has this fields ( Id, name, origin, date, provider )
I want a query where I get a product info and in the same register the info of the productversion with the max date, something like this:
select p.ProductId, p.ProductName , max(pv.date), name of max(pv.date), origin of max(pv.date) from Product p Join ProductVersion pv on p.ProductId = pv.ProductId where userId = 'test_user' group by p.Id
I want to create a view to call from c#, I am working with linq but the performace for this case is not good, so I am trying with a view with the info I need. Something like this I want to achieve with a SQL query.
var result = _context.ProductVersion .Where(x => x.UserId == userId) .GroupBy(x => x.ProductId) .Select(group => group.OrderByDescending(x => x.Date).FirstOrDefault()) .Include(x => x.Product) .ToList();
Advertisement
Answer
This should do it.
DECLARE @userID NVARCHAR(100) = N'test_user' WITH cte AS ( SELECT p.ProductID ,p.ProductName ,pv.Date as VersionDate ,pv.Name as VersionName ,pv.Origin as VersionOrigin ,ROW_NUMBER() OVER (PARTITION BY p.ProductID ORDER BY pv.Date DESC) as PartitionID FROM product p inner join ProductVersion pv on p.ProductId = pv.ProductID WHERE userID = @userID ) SELECT ProductID ,ProductName ,VersionDate ,VersionName ,VersionOrigin FROM cte WHERE PartitionID = 1