function to_char(unknown, unknown) is not unique

[Alex Bozhenko]

Hello.

When I'm trying to:
select to_char("ISDate", 'DD.MM.YYYY')::text from register."KSPT_view"
from table, containing nulls in "ISDate", i get nulls and formatted date as
output.

But when I'm trying to:
select to_char(null, 'DD.MM.YYYY')::text

I get a error message:

ERROR: function to_char(unknown, unknown) is not unique
LINE 1: select to_char(null, 'DD.MM.YYYY')::text
^
HINT: Could not choose a best candidate function. You might need to add
explicit type casts.

********** Error **********

ERROR: function to_char(unknown, unknown) is not unique
SQL state: 42725
Hint: Could not choose a best candidate function. You might need to add
explicit type casts.
Character: 8

[Bartosz Dmytrak]

hi,
try SELECT to_char(null::date, 'DD.MM.YYYY')::text or SELECT
to_char(null::timestamp, 'DD.MM.YYYY')::text

should work.
It is not possible to guess type of null without explicit cast.

Regards,
Bartek

[Alex Bozhenko]

Ok, i have understand.

Select from table works because of type date of column.

Thanks!

Post by Bartosz Dmytrak
hi,
try SELECT to_char(null::date, 'DD.MM.YYYY')::text or SELECT
to_char(null::timestamp, 'DD.MM.YYYY')::text
should work.
It is not possible to guess type of null without explicit cast.
Regards,
Bartek