On Thu, Apr 28, 2011 at 12:46:50PM -0700, Basil Bourque wrote:
> In PL/pgSQL, how does one generically access the fields of the OLD or NEW record?
> I've tried code such as this:
> 'NEW.' || quote_ident( myColumnNameVar ) || '::varchar'
> But when run by an "EXECUTE" command, I get errors such as:
> ERROR: missing FROM-clause entry for table "old"
> SQL state: 42P01
> It seems that I cannot get PL/pgSQL to interpret the text of "NEW." + column name as text.
> My goal is to loop each field in a trigger, comparing the "OLD." & "NEW." values of each field. If different I want to log both values in a history/audit-trail table.
> Is there some way to loop the fields of a trigger's Record? I've read other people's frustration at not being able to get an array of fields from the Record.
> My approach is to fake it: Get the table's columns and data types by querying the meta-data tables (pg_attribute, pg_class, pg_type). But I cannot get "NEW." || colNameVar to be interpreted. Perhaps there is a better approach.
long story short - it's not possible.
a bit longer story:
there are couple of workarounds.
1. you can use hstore datatype and it's casts from record to hstore
2. you can use another pl/* language - like pl/perl - which doesn't have
3. you can use ready made tool for auditing that does what you want, so
you don't have to worry ( http://pgfoundry.org/projects/tablelog/ )
but really, read, and understand the warnings.
The best thing about modern society is how easy it is to avoid contact with it.
In response to
pgsql-general by date
|Next:||From: John DeSoi||Date: 2011-04-28 20:08:26|
|Subject: Re: "OLD." || myColumnNameVar (How to generically access columns in a trigger's OLD or NEW records)|
|Previous:||From: Basil Bourque||Date: 2011-04-28 19:46:50|
|Subject: "OLD." || myColumnNameVar (How to generically access columns in a
trigger's OLD or NEW records)|