[Info-ingres] why is an empty string an integer

[aw at rationalcommerce.com]

MorningIf you use zero instead of 1 do you get the same?I must admit i have not seen that 'when a is integer/float' syntax before.But then i use openroad so our syntax is about 20 years behind.Adrian------ Original message------From: Martin BowesDate: Wed, 29 Jul 2020 08:01To: Ingres lists;Cc: Subject:[Info-ingres] why is an empty string an integer

Hi All,
 
I may have come across this before, but it’s early and I haven’t had my coffee.
 
declare global temporary table fred(
    a varchar(20)
) on commit preserve rows with norecovery;
Executing . . .
 
continue
* * insert into fred values (null), (''), ('1'), ('13-jan-2020');
Executing . . .
 
(4 rows)
continue
* * * * * * * * select case when a is null then 'null'
            when a = '' then 'empty string'
            else a end as data,
       case when a is integer then 'integer' else 'not integer' end as is_integer,
      case when a is float then 'float' else 'not float' end as is_float,
       case when a is ansidate then
 'ansidate' else 'not ansidate' end as is_ansidate
from fred;
Executing . . .
 
 
┌────────────────────┬───────────┬─────────┬────────────┐
│data                │is_integer │is_float │is_ansidate │
├────────────────────┼───────────┼─────────┼────────────┤
│null                │not integer│not float│not ansidate│
│empty string        │integer    │float    │not ansidate│
│1                   │integer    │float    │not ansidate│
│13-jan-2020         │not integer│not float│ansidate    │
└────────────────────┴───────────┴─────────┴────────────┘
(4 rows)
continue
 
Now the tests with nulls behave as I expect. But the empty string cases I did not expect. Is this a bug? Documented behaviour?
 
Martin Bowes

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