Re: NULL in arrays

On Monday 06 November 2006 20:16, Jim C. Nasby wrote:
> On Sun, Nov 05, 2006 at 09:53:08PM +0100, Martijn van Oosterhout wrote:
> > Note that the constructs:
> >
> > ARRAY['a',"NULL",'c']
> >
> > and
> >
> > '{a,"NULL",c}'
> >
> > are *completely* different. The first is a special array constructor
> > and all its parameters are normal SQL expressions, so you can reference
> > columns and use NULL directly without quotes. The latter is the string
> > value of the array, which is specially decoded. Thats why the latter
> > treats the double quotes differently.
>
> This could probably be expanded on in the docs... mentioning the
> difference in the NULLs section would be a good start. IE:
>
> To set an element of an array constant to NULL, write NULL  for the
> element value. (Any upper- or lower-case variant of NULL will do.) If
> you want an actual string value "NULL", you must put double quotes
> around it. Note that if you use the ARRAY construct you should just use
> a bareword NULL instead.

This is not terribly clearer :-)  Hopefully we can put examples along with it, 
since that helps out tremendously. 

-- 
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL