Re: Check constraints do not seem to be working!!!

[Pavel Stehule]

st 11. 11. 2020 v 9:38 odesílatel Chris Sterritt <chris.sterr...@yobota.xyz>
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
>
>