Re: Truncate if exists

On Fri, Oct 12, 2012 at 5:52 PM, Dimitri Fontaine
<dimitri(at)2ndquadrant(dot)fr> wrote:
> Christopher Browne <cbbrowne(at)gmail(dot)com> writes:
>> I suggest the though of embracing statement modifiers in DDL, with
>> some options possible:
>> a) { DDL STATEMENT } IF CONDITION;
>> b) { DDL STATEMENT } UNLESS CONDITION;
>
> Just saying. I hate that. Makes it harder to read, that last bit at the
> end of the command changes it all. It's cool for a linguist, I guess,
> but we're not typing sentences at the psql prompt…

I could see it being
WHEN CONDITION { STATEMENT } OTHERWISE { STATEMENT };

It's all a strawman proposal, where I'm perfectly happy if there's
something people like better. I like to think this is cleaner than
the present proliferation of {IF EXISTS|IF NOT EXISTS}, but if others
don't concur, there's little point to taking it further.

>> where CONDITION has several possible forms:
>> i) {IF|UNLESS} ( SQL expression returning T/F )
>> ii) {IF|UNLESS} {EXISTS|NOT EXISTS}
>> {TABLE|SCHEMA|COLUMN|FUNCTION|...} object_name
>
> Now we're talking about T-SQL? Sorry, I suppose you didn't mean to lead
> us that way, but I couldn't resist comparing. Soon enough you want a
> full programming language there.

Heh. Next, I'll be proposing LETREC*, or of adopting the EVERY
operator from Icon, and coroutines from BCPL :-). Keen on LOOP? :-)

The fact that we now have WITH RECURSIVE does extend what's reasonable
to hope for :-).
--
When confronted by a difficult problem, solve it by reducing it to the
question, "How would the Lone Ranger handle this?"