Re: declare variable in trigger

harun.bolat_at_netsim.net wrote:
> thanks,
>
> I have posted trigger only to simplify an example.
>
> as example firebird trigger like this.
> variable of CARI_ISLEM_NO same as field name.
No it is not!
:CARI_BAGLANTI_NO2 != CARI_BAGLANTI_NO2 If you can place a ":" in front of every occurance of the variable, why not a "v_"?
Firebird is taking the "easy way out" of name resolution. It is in violation of the SQL standard.
I find it interesting that in some places the ':' appears to be needed while in others it is not. What are the rules? E.g.: "IF(FIRMA_NO1 <> FIRMA_NO2) THEN", and "DECLARE VARIABLE FIRMA_NO1 INTEGER" no ":" here.

I understand that Oracle and Firebird are different, but they have different syntax to begin with. By no means is the variable resolution any better that PL/SQLs. In fact PL/SQL appears to be closer to ANSI SQL/PSM with that respect.
SQL name resolution defines that all identifiers are resolved from the inside out. That is you start with the inner most object (e.g. a scalar subquery table reference), then work yourself outside to finally the outermost table references. If the name cannot be resolved it must be either (in order):

1. A local variable
2. A trigger variable/routine parameter
3. A global variable

Any conflicts can be overcome with labels/schema names (such as NEW in case of a trigger). Just like in real life family names are used if you refer to John and it's not obvious you mean the John standing right next to you.

Cheers
Serge

-- 
Serge Rielau
DB2 Solutions Development
IBM Toronto Lab

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