Save/Update List of Dates in Database - sql-server-2008

Question

I'm using SQL Server 2008. I'm looking for a creative way to save and update a list of dates in our database.
I'm going to collect a list of dates from the application and I will need to check if each value already exists, if not add, and then delete any dates not in the list that are already stored in the database.
The easiest thing I can think of is to delete all dates associated to this particular request and then iterate over each item in my list and insert into database.
Does anyone have a more elegant idea?

Answer 1

You can use merge. You can also load the dates into a temporary table and do an insert such as:
with toinsert as (
select thedate
from #newdates nd left outer join
alldates ad
on nd.thedate = ad.thedate
where ad.thedate is null
)
insert into alldates(thedate)
select thedate
from toinsert
The toinsert alias uses a left outer join to do a "not in". I often find that this works better. Regardless of how you set up the queries (like this or with a merge), you should put in an index on the dates. It should make things go faster.

Answer 2

I would use a combination of table valued parameters and the NOT EXISTS function. So pass your dates from your application to a stored procedure as a paramater, the stored procedure will then return a list of all the dates inserted back to your application.#
The first step is to create the type so you can pass a list of dates to your procedure:
CREATE TYPE dbo.DateListType AS TABLE (Date DATETIME)
Next create your procedure. I have assumed you date table is called dbo.Dates, you'll obviously need to substitute your table in for this.
CREATE PROCEDURE dbo.InsertDates (#Dates dbo.DateListType READONLY)
AS
BEGIN
DECLARE #Inserted TABLE (Date DATETIME)
INSERT INTO dbo.Dates
OUTPUT inserted.Date INTO #Inserted
SELECT Date
FROM #Dates d
WHERE NOT EXISTS
( SELECT 1
FROM dbo.Dates
WHERE Dates.Date = d.Date
)
SELECT Date
FROM #Inserted
END
Not sure what your application is coded in so unfortunately can't suggest any code to call the procedure