Sergey Karin wrote:
Hi, List!
I'm using PG8.1.
Are there any abilities to represent NULL values as string?
Null isn't a real value. Try not to think of it as a value.
http://archives.postgresql.org/pgsql-sql/2003-01/msg00222.php
num_value alias for $1;
string_value := \'input value = \' || num_value;
If I einvoke my function with NULL argument, it return NULL. But I want
'input value = NULL'.
Because NULL means unknown. A string with an unknown string appended to
it is itself unknown.
Of course, I can check input value like this:
if(num_value isnull) then
string_value := \'input value = NULL\';
else
string_value := \'input_value = \' || num_value;
end if;
But it is not laconic...
Try something like:
string_value := ''input_value = '' || COALESCE(num_value, 'a null');
--
Richard Huxton
Archonet Ltd
