Re: proposal: doc: simplify examples of dynamic SQL

Bruce Momjian wrote:
> On Fri, Mar 20, 2015 at 08:54:24AM -0700, David G. Johnston wrote:

> > 1. The layout of the format version is different, with respect to newlines,
> > than the quote version; but while using newlines for the mandatory
> > concatenation is good having an excessively long format string isn't desirable
> > and so maybe we should show something like:
> > 
> > EXECUTE format('SELECT count(*) FROM %I '
> > || 'WHERE inserted_by = $1 AND insert <= $2', tabname)
> > INTO c
> > USING checked_user, checked_date
> 
> I think that is very confusing --- the idea is that we don't need to use
> || with format, but you are then using || to span multiple lines.

That || seems fine, since it's only used for a line continuation; having
|| scattered all over the query string to interpolate each variable is
much more unreadable.

That said, the || there is unnecessary because per standard two literals 'lit1'
'lit2' 
are concatenated if they are separated by a newline.  So this
EXECUTE format('SELECT count(*) FROM %I ' 'WHERE inserted_by = $1 AND insert <= $2', tabname)INTO cUSING checked_user,
checked_date

should suffice.


BTW very long lines are undesirable because they are truncated in the
PDF output.

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services