Re: Robust ways for checking allowed values in a column

On 1/25/22 09:35, Shaozhong SHI wrote:
> How about adding null as an alteration.
>
> Would this be robust?
>
> Regards,
>
> David
>
> On Tue, 25 Jan 2022 at 14:25, David G. Johnston
> <david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
>
> On Tue, Jan 25, 2022 at 6:56 AM Shaozhong SHI
> <shishaozhong(at)gmail(dot)com> wrote:
>
>  select form from mytable  where form ~
> '^Canal$|^Drain$|^Foreshore$|^inlandRiver$|^Lake$|^lockOrFlightOfLocks$|^Marsh$|^Researvoir$|^Sea$|^tidalRiver$|^Transfer$'
>
>
> You do not need to repeat the boundary metacharacters on each
> branch.  You can assert their presence just once and then use
> parentheses to group the alternations.
>
> form ~ '^(?Canal|Drain|etc...)$'
>
> David J.
>

You would need to add form ~ 'expression' or form is null

And a body of held water is a reservoir (no 'a')