How to check for a blank date value in Ingres

Question

I have an Ingres table with date field (data type ingresdate) which has a not null restriction. However blank i.e. empty values are allowed. How can you check for a blank value?

Of course testing for null values using ifnull() does not work - as per example below.

INGRES TERMINAL MONITOR Copyright 2008 Ingres Corporation
Ingres SPARC SOLARIS Version II 9.2.3 login
continue
create table test ( id integer not null, date_field ingresdate not null with default )\g
insert into test (id, date_field) values ( 1, '' )\g
insert into test (id, date_field) values ( 2, '31/12/2014' )\g
continue
(1 row)
continue
select id, date_field, ifnull( date_field, '01/01/2014' ) as test_field from test\g
(1 row)
continue
+-----------------------------------------------------------------+
¦id           ¦date_field               ¦test_field               ¦
+-------------+-------------------------+-------------------------¦
¦            1¦                         ¦                         ¦
¦            2¦31/12/14                 ¦31/12/14                 ¦
+-----------------------------------------------------------------+
(2 rows)
continue
\q
Your SQL statement(s) have been committed.
Ingres Version II 9.2.3 logout

Answer 1

Actually, thanks to PaulM, I figured it out:

INGRES TERMINAL MONITOR Copyright 2008 Ingres Corporation
Ingres SPARC SOLARIS Version II 9.2.3 login

select id, date_field, 
case when date_field = '' then '01/01/2014' else date_field end as test_field 
from test
+-----------------------------------------------------------------+
¦id           ¦date_field               ¦test_field               ¦
+-------------+-------------------------+-------------------------¦
¦            1¦                         ¦01/01/14                 ¦
¦            2¦31/12/14                 ¦31/12/14                 ¦
+-----------------------------------------------------------------+
(2 rows)

Ingres Version II 9.2.3 logout