Re: except command

On Mon, 13 Aug 2007 13:07:43 -0500
"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:

> >>> On Mon, Aug 13, 2007 at 12:50 PM, in message <46C099F6(dot)8050002(at)cerene(dot)fr>,
> olivier boissard <olivier(dot)boissard(at)cerene(dot)fr> wrote:
> > I tried to use the except command in postgresql 8.1
> > I don't understand as it works
> > When I read doc , I understand that it was like a difference betwwen two
> > queries
>
> That isn't how I read it:
>
> "The EXCEPT operator returns the rows that are in the first result set
> but not in the second."
>
> ( http://www.postgresql.org/docs/8.1/interactive/sql-select.html )
>
> Are you seeing something different?
>
> This gets me all the eye color codes that don't start with the letter 'B'.
> (There are of course easier ways to get that...)
>
> bigbird=> select * from "EyeColorCode" except select * from "EyeColorCode" where "eyeColorCode" like 'B%';
> eyeColorCode | descr | isActive | dotEyeColorCode
> --------------+-----------------+----------+-----------------
> GRN | Green | t | GRN
> GRY | Gray | t | GRY
> HAZ | Hazel | t | HAZ
> MAR | Maroon | t | MAR
> MUL | Multicolored | t | DIC
> PNK | Pink | t | PNK
> XXX | Unknown | t | UNK
> (7 rows)
>
> -Kevin
so is this faster than usiung 'where not exists' ??

Steve