On 1/24/19 3:04 AM, Alexandre GRAIL wrote:
Hello the list,
Maybe this question has been debated before (I didn't find anything
helpful) but :
Why the default is to throw an error when casting Integer to Boolean in
assignment, and accepting it everywhere else ?
The overall reason:
https://www.postgresql.org/docs/8.3/release-8-3.html
E.24.2.1. General
Non-character data types are no longer automatically cast to TEXT
(Peter, Tom)
Previously, if a non-character value was supplied to an operator or
function that requires text input, it was automatically cast to text,
for most (though not all) built-in data types. This no longer happens:
an explicit cast to text is now required for all non-character-string
types. For example, these expressions formerly worked:
So you can type :
postgres=# select 1::boolean;
bool
------
t
(1 row)
or
postgres=# select 0::boolean;
bool
------
f
(1 row)
But you *cannot* use 1 or 0 as valid input for boolean type when
inserting or updating :
test=# CREATE TABLE test1 (a boolean);
CREATE TABLE
test=# INSERT INTO test1 VALUES (1);
ERROR: column "a" is of type boolean but expression is of type integer
LINE 1: INSERT INTO test1 VALUES (1);
^
HINT: You will need to rewrite or cast the expression.
This behavior cannot be changed, as this cast is hard coded with
"Implicit?=no".
And added to this weirdness is the fact that '1' or '0' (with quote) is OK.
So is there a reason to forbid 0 and 1 as valid boolean, without
explicit cast ?
Thanks!
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
