I just woke up from a dream which, since I remember it, I'll blog it...
The dream was that I was back working in the Co-op in Ruthin, with all of its original staff (original from my point of view - they were there when I started). Tom (the manager, who became regional manager), Mike (the deputy manager, who became manager of Co-op Rhyl), Ben (floor staff), all of the till girls, everyone...
For whatever reason, in the dream I'd gone back there and was doing a part time job (16 hours a week, evenings and weekends) stacking the shelves again. It had to be part time in order to fit around my current work at Cogenta.
So, I'm back, really happy to see everyone again and it's the end of the evening. There's a new guy (who looks suspiciously like someone from Denbigh High School) and I've discovered that noone bothers to tidy the shelves up any more (I never really worked out whether it was called facing-up or facing-off). I start to tidy an isle, but I've only really just started when it hits 10 o'clock and it's time to go home. But instead of going home, all the staff go outside and start playing basketball, which I'm crap at. At one point, I do this really nice slow-mo slamdunk and the ball still doesn't go in. We laugh about it and the dream ends.
I'll work out what it all means later.
Imagine the following Database setup
TableA has an ID column, AID
TableB has an ID column, BID
Table AB has 2 columns, AID and BID which realte to the IDs from TableA and TableB respectively.
Now imagine you want to delete one of the references between an A and a B from TableAB, easy.
DELETE FROM TableAB WHERE AID = @AID and BID = @BID
Now tidy up so that any As that aren't referenced by a B are removed
DELETE FROM TableA WHERE AID NOT IN (SELECT AID FROM TableAB)
You might want to throw those two lines in a stored procedure, call it DeleteAB. Now how do we delete all AIDs which are referenced by a specific BID whilst still keeping TableA as clean/empty as possible? One of two ways...
--Get a list of the used AIDs for the specific BID
DECLARE @AIDList CURSOR FOR
SELECT a.AID FROM TableA a INNER JOIN TableAB ab ON ab.AID = a.AID WHERE ab.BID = @BID
--Loop through the keyword list, calling the StoredProc (DeleteAB) to take care of the acutal deletion
DECLARE @Current_AID int
OPEN @AIDList
FETCH NEXT FROM @AIDList INTO @Current_AID
WHILE @@FETCH_STATUS = 0
BEGIN
exec DeleteAB @Current_AID, @BID
FETCH NEXT FROM @AIDList INTO @Current_AID
END
CLOSE @AIDList
DEALLOCATE @AIDList
Or the quicker way...
DELETE FROM TableAB WHERE BID = @BID
DELETE FROM TableA WHERE AID NOT IN(SELECT AID FROM TableAB)
The thing is, whilst I much prefer reading the SQL code for the second version, I hate the lack of architecture behind it. If we make an alteration to the Database so that A is not used somewhere else, the first example need only alter the StoredProc, whereas the second solution would need an alteration for both the single deletion and multiple deletion methods. In the world of a normal programming language (C# as an example) we'd more than likely go with the architecturally sound version -
public void DeleteAB(int AID, int BID)
{
//Code to remove AB
}
public void DeleteAllAForB(int BID)
{
//Foreach AID related to BID
{
DeleteAB(AID, BID);
}
}
Why do we get sloppy on the design with SQL? Because we need the performance of the inline code. Not that I like it.
I was reading this article (
Microsoft Surfaces finds home in AT&T stores) when I wondered how many people wont understand the idea of dragging an icon on a touchscreen. Think about it - a big icon on a monitor looks like a button, so you expect to press it. Thanks to the last 30 years of computing, we expect to be able to click/press most things on a monitor and although dragging might make a lot more sense from some angles (to put a ringtone on the phone you drag the ringtone to the phone) we've had too many years of clicking-not-dragging to expect this change to work overnight. Is this what's preventing more touch specific applications for the tablet PC? And how did Apple manage to do touch so right with the iPhone?
