Optionally saving selectively data in one-go only when you want it - sql-server

Question

I have a table where data does not initially exist until an action is taken that stores all settings made by client in one-go. To illustrate this simply, a button click that stores all column values off a (HTML) table into a database table (let's call this dbo.Settings).
So instead of inserting into this dbo.Settings all the default values prior to user making any changes to their individual settings (ever), I kind of created the pseudo data for them that will be returned whenever requested, kind of like SELECT-ing the default values:
SELECT
CanView = ISNULL(CanView, 1),
CanRead = ISNULL(CanRead, 1),
CanWrite = ISNULL(CanWrite, 0)
FROM
dbo.Settings AS s
WHERE
UserId = #id
Rather than doing:
IF NOT EXISTS(SELECT * FROM dbo.Settings WHERE UserId = #id)
BEGIN
INSERT INTO dbo.Settings (UserId, CanView, CanRead, CanWrite)
VALUES (#id, 1, 1, 0)
END
The problem with this is whenever I need to add a new setting column in the future, I now have to note one more procedure to modify/add the default value for this column as well -- which I don't like. Using TRIGGER would be an option but I wonder what the best practice in managing data like this would be. Or would you do something like this:
CREATE PROC Settings_CreateOrModify
#userId INT,
#canView BIT = NULL,
#canRead BIT = NULL,
#canWrite BIT = NULL
AS
BEGIN
IF EXISTS(SELECT * FROM dbo.Settings WHERE UserId = #userId) BEGIN
UPDATE s
SET
CanView = #canView,
CanRead = #canRead,
CanWrite = #canWrite
FROM
dbo.Settings AS s
WHERE
s.UserId = #userId AND
(#canView IS NULL OR #canView <> s.CanView) AND
(#canRead IS NULL OR #canRead <> s.CanRead) AND
(#canWrite IS NULL OR #canWrite <> s.CanWrite)
END
ELSE BEGIN
INSERT INTO
dbo.Settings(UserId, CanView, CanRead, CanWrite)
SELECT
#userId, #canView, #canRead, #canWrite
END
END
How would you handle data structure like this? Any recommendation or correction would be greatly appreciated. Thanks in advance!

Answer 1

Your SP is a good way to go, and doing it like this is commonly called an "UPSERT".
It also looks to me as if the block:
(#canView IS NULL OR #canView <> s.CanView) AND
(#canRead IS NULL OR #canRead <> s.CanRead) AND
(#canWrite IS NULL OR #canWrite <> s.CanWrite)
is problematic since it causes the UPDATE to run only if ALL parameters changed their value. I don't think that's what you wanted to say. Just SET the three values regardless of what's already there.
You still end up with three places to change when you add a new setting: The Table, the Upsert and the Defaults.
One very different approach is this:
Apply the defaults to the columns in the table definition.
Whenever you need the values for a new user, do: INSERT INTO dbo.Settings(UserId) The defaults will fill the rest of the columns.
Now you can retrieve the values for ALL users (new or not) in the same way from the table.
Since you already inserted the user in step 2, you know the userid is there already and you can always save the changes via a simple update.
This eliminates the SP and the need of providing the defaults in one extra place.