2010/9/28 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
>> I looked on some constructs that helps with iteration over array in
>> plpgsql. I propose a following syntax:
>> FOR var IN [array variable | array expression]
> I don't have any opinion about whether the functionality proposed here
> is worth the trouble, but I do have an opinion about that syntax: it's
> an awful choice. plpgsql has enough trouble already distinguishing
> between integer for-loops and query for-loops, not to mention trouble
> in producing a helpful error message when somebody gets either of those
> constructs slightly wrong. Providing a variant where a single
> expression can follow IN will make both of those problems an order of
> magnitude worse. As an example, is this a for-in-query or a
> FOR v IN (SELECT arraycol FROM tab) LOOP ...
This is a subquery - so it is a for-in-array - should return one row
with one column. Similar construct is in SQL/PSM
where you can to write SET var = (SELECT ...)
You cannot to write just (SELECT ...) anywhere
> Either answer is plausible depending on whether you assume the
> parentheses make it a subquery.
> Pick something less easily confusable with the existing constructs.
It's not simple - FOR i IN array is natural - Original ADA use a very
FOR i IN ARRAY has problem with constant array - FOR i IN ARRAY ARRAY[1,2,3,]
and FOREACH is used in Oracle for absolutely different task.
we have now a for-in-cursor, so there is a precedent.
> regards, tom lane
In response to
pgsql-hackers by date
|Next:||From: Pavel Stehule||Date: 2010-09-28 19:48:36|
|Subject: Re: Proposal: plpgsql - "for in array" statement|
|Previous:||From: Heikki Linnakangas||Date: 2010-09-28 19:14:22|
|Subject: Re: patch: SQL/MED(FDW) DDL|