Sounds like a good and usefull feature to me!

Giulio

--- In Firebird-Architect@yahoogroups.com, Alexandre Benson Smith
<iblist@t...> wrote:

> Hi !
>
> I have read th FB 2.0 RoadMap, and wish to ask for a feature request.
>
> I have discussed this on firebird-support some time ago.
>
> What I think could be implemented in FB is a UPDATED function that will
> run insed triggers, this function will be used to test if a column was
> modified.
>
> In triggers I use to do this
>
> If (
> (Old.Quantity <> New.Quantity) or
> ((Old.Quantity is null) and (New.Quantity is not null)) or
> ((Old.Quantity is not null) and (New.Quantity is null))
> ) then
>
> This will be changed by
>
> if Updated(ColumnA) then
>
> in delete or insert triggers UPDATED always return true, and in update
> triggers should work as above.
>
> The readability is, IMHO, very increased, mainly when one wish to test
> multiple columns like this
>
> if (Updated(Quantity) or Updated(Price) or Updated(Discount)) then
> SP_SalesItemCalcNetValue(new.SalesItemID)
>
> that is far more simple, less suitable for errors and easier to read
> than the actual version that is
> if (
> (Old.Quantity <> New.Quantity) or
> ((Old.Quantity is null) and (New.Quantity is not null)) or
> ((Old.Quantity is not null) and (New.Quantity is null)) or
>
> (Old.Price <> New.Price) or
> ((Old.Price is null) and (New.Price is not null)) or
> ((Old.Price is not null) and (New.Price is null)) or
>
> (Old.Discount <> New.Discount) or
> ((Old.Discount is null) and (New.Quantity is not null)) or
> ((Old.Discount is not null) and (New.Discount is null))
> ) then
> SP_SalesItemCalcNetValue(new.SalesItemID)
>
>
> Now, with Coalesce this could be simplified to:
>
> if (
> (Coalesce(Old.Quantity, -9999 ) <> Coalesce(New.Quantity, -9999) or
> (Coalesce(Old.Price, -9999 ) <> Coalesce(New.Price, -9999) or
> (Coalesce(Old.Discount, -9999 ) <> Coalesce(New.Discount, -9999)
> ) then
> SP_SalesItemCalcNetValue(new.SalesItemID)
>
> Only if you are sure that the value -9999 will never be a valid values
> for the tested columns...
>
> Anyone think this could be done ?
> Is this a simple thing to do ?
>
> see you !
>
> --
>
> Alexandre Benson Smith
> Development
> THOR Software e Comercial Ltda.
> Santo Andre - Sao Paulo - Brazil
> www.thorsoftware.com.br