select in check constraint - sql-server-2008

Question

I want to create a check constraint for my table, where you can't add new line, if the new booking range(start_date, end_date) have intersect with an already submitted row.
But i can't place query in a check constraint. Do you have an idea how to do this?
The tables:
APARTMAN
id INT
price INT
BOOKINGS
id INT
start_date DATE
end_date DATE
apartman_id INT
[apartman_id] IN (SELECT [id] FROM [dbo].[APARTMAN]
WHERE [id] NOT IN (
SELECT [apartman_id] FROM
[dbo].[BOOKINGS]
WHERE
([start_date] <= "requested end_date" AND
[end_date] >= "requested start_date" )
OR
([start_date] <= "requested start_date" AND
[end_date] >= "requested end_date" )
OR
(([start_date] <= "requested end_date" AND [end_date] >= "requested start_date" )
OR
([end_date] <= "requested start_date" AND [end_date] >= "requested end_date" ))
)
)

Answer 1

Here's an instead of trigger that I think handles all scenarios.
CREATE TRIGGER dbo.PreventOverlappingBookings
ON dbo.BOOKINGS INSTEAD OF INSERT, UPDATE
AS
BEGIN
SET NOCOUNT ON;
IF EXISTS (
SELECT 1 FROM inserted AS i
INNER JOIN dbo.BOOKINGS AS b
ON (b.id <> i.id OR i.id = 0) -- 0 for insert
AND b.apartman_id = i.apartman_id
AND ((b.start_date <= i.end_date AND b.end_date >= i.start_date)
OR (b.start_date <= i.start_date AND b.end_date >= i.end_date)
OR (b.end_date <= i.start_date AND b.end_date >= i.end_date))
) OR EXISTS (
-- also make sure there are no overlaps in a set-based insert/update
SELECT 1 FROM inserted AS i
INNER JOIN inserted AS b
ON (b.id <> i.id OR i.id = 0) -- 0 for insert
AND b.apartman_id = i.apartman_id
AND ((b.start_date <= i.end_date AND b.end_date >= i.start_date)
OR (b.start_date <= i.start_date AND b.end_date >= i.end_date)
OR (b.end_date <= i.start_date AND b.end_date >= i.end_date))
)
BEGIN
RAISERROR('Overlapping date range.', 11, 1);
END
ELSE
BEGIN
UPDATE b SET start_date = i.start_date, end_date = i.end_date
FROM dbo.BOOKINGS AS b
INNER JOIN inserted AS i
ON b.id = i.id;
IF ##ROWCOUNT > 0
BEGIN
INSERT dbo.BOOKINGS(start_date, end_date, apartman_id)
SELECT start_date, end_date, apartman_id FROM inserted AS i;
END
END
END
GO
Some answers will suggest a function in a UDF, but I don't trust them (and neither should you, IMHO).