"Jerry Stuckle" <jstucklex@attglobal.net> schreef in bericht
news:eOednZcnMt7jWDzanZ2dnUVZ_ournZ2d@comcast.com. ..
> Geoff wrote:
>> Captain Paralytic wrote:
>>> On 31 Jan, 10:29, Geoff <foooooo...@hotmail.com> wrote:
>>>> SELECT * , DATE_ADD( test_equipment_cal_date, INTERVAL
>>>> test_equipment_cal_days DAY ) AS test_equipment_expire_date
>>>> FROM `test_equipment`
>>>> WHERE test_equipment_expire_date < '2008-01-31'
>>>>
>>>> #1054 - Unknown column 'test_equipment_expire_date' in 'where clause'
>>>>
>>>> so, i simply can't do that ???
>>>> how am i supposed to do such a thing ?
>>>
>>> Put it in the HAVING clause instead
>>
>> nice one
>>
>> was the first thing that came to mind
>> i though you used that with group by only though
>>
>> got it working
>>
>
> That is true in ANSI SQL. MySQL extends that functionality.
>
> Personally, I wish ANSI would pick up on MySQL's way of doing things. I
> see no logical reason for the restriction, and the syntax can be very
> handy.
>
> Otherwise you have to repeat the entire calculated expression in the WHERE
> clause. A good optimizer should recognize that, but who knows?
>

the disadvantage of some people writing

SELECT name FROM persons HAVING name='Santa';

will stop this from becoming ANSI, i guess.....