Re: Advice for generalizing trigger functions

[Erik Jones <erik(at)myemma(dot)com>]

On Dec 27, 2007, at 12:03 PM, Richard Broersma Jr wrote:

> --- On Thu, 12/27/07, Erik Jones <erik(at)myemma(dot)com> wrote:
>
> > TG_TABLE_NAME will have the name of the table the trigger
> > was fired  on.  With that and using EXECUTE for your INSERT
> > statements, you'll  probably be set.
>
> True the table name is the easy part, but how do I determine the  
> Primary Key components of the table that will also be needed in the  
> SQL string that will be executed?

That depends on how generalized you want this trigger function to  
be.  If you have a set number of tables you can branch on the table  
name to determine the id column.   That's brittle and would require  
updating the the function every time you want to use if for a new  
table type but if there's a limited number of tables it may work for  
you.  Another way to go would be to the table name to join across  
pg_class, pg_attribute, and pg_constraint.  Take a look at the table  
layouts for those in the manual and it should be pretty clear how to  
do that.

Erik Jones

Software Developer | Emma®
erik(at)myemma(dot)com
800.595.4401 or 615.292.5888
615.292.0777 (fax)

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