st 11. 11. 2020 v 9:38 odesílatel Chris Sterritt <chris.sterritt@xxxxxxxxxx> napsal:
On 11/11/2020 06:44, Jitendra Loyal wrote:
Consider this table definition:
create table t ( i serial, b bool, c bool,
constraint b_c check ( (b = true and c is not null ) or (b is distinct
from true and c is null) )
constraint b_c check ( (b = true and c is not null ) or (b = false and c
is null) or (b is null and c is null) )
);
Despite the above two constraints, the following rows get into the table:
insert into t (b , c) values (null, true), (null, false);
(b = TRUE AND c IS NOT NULL) evaluates to null when b is null
yes, constraint is violated only when result is false, no when it is null.
Regards
Pavel
Cheers, Chris Sterritt
