Re: Planning error in dynamic string creation in plpgsql

On 01/06/2014 07:42 AM, David Johnston wrote:
> Adrian Klaver-3 wrote
>>>
>>>
>>> In the real function I'm writing, the columns to be used in the string
>>> being created are pulled from a configuration table, so their types
>>> could be anything. So casting the quote_literal() calls is not really an
>>> option here.
>>>
>>> Any help would be appreciated.
>>
>> Cast before the quote_literal?
>>
>> Example:
>>
>> EXECUTE 'SELECT min('||v_col||'::text) as min, max('||v_col||'::text) as
>> max FROM test_temp' INTO v_record;
>
> Right idea if the loss of original type in the min/max query is acceptable
> (which it should be).  But the cast wants to be of the min/max RESULT not
> the min/max INPUT.
>
> SELECT min(' || v_col || ')::text AS min_text, max(' || v_col || ')::text AS
> max_text FROM ...
>
> Min/Max logic wants to be done by the rules for the original type, not
> according to string collation rules.

Yes, that would be the way to do it.

>
> David J.
>
>
>
>
>


--
Adrian Klaver
adrian.klaver@gmail.com