Update count column from data in another table

Question

In my DB I have two tables Items(Id, ..., ToatlViews int) and ItemViews (id, ItemId, Timestamp)

In ItemViews table I store all views of an item as they come to the s

Answer 1

I found this question / answer a year after it was written and answered. the answer was okay, but I was after something a bit more automatic. I ended up writing a trigger to automatically recalculate the column when a relevant row in the other table was inserted, deleted or updated.

I think it's a better solution than running something manually to do the recalculation as there isn't any possibility of someone forgetting to run the code:

CREATE TRIGGER [dbo].[TriggerItemTotalViews] 
   ON  [dbo].[ItemViews]
   AFTER INSERT, DELETE, UPDATE
AS 
BEGIN
SET NOCOUNT ON;

UPDATE [Items] 
SET [TotalViews] = 
    (
    SELECT COUNT(id) 
    FROM [ItemViews] 
    WHERE [ItemViews].[ItemId] = [Items].[ItemId]
    )
WHERE [Items].[ItemId] IN
    (
    SELECT [ItemId] FROM [INSERTED] 
    UNION 
    SELECT [ItemId] FROM [DELETED]
    )
END