>>Hi Jim,
>>
>>>>When i execute the folowing SQL query, i get the error colomn "WTG"not found.
>>>>
>>>>SELECT detail.avr_ari,;
>>>> iif(Detail.avr_wtg=.t.,'J','N') as WTG;
>>>>FROM general!detail;
>>>>WHERE WTG='J'
>>>>
>>>>Is this an impossible kind of query, to include an expressionalias in the WHERE Clause ?
>>>>
>>>>Any idea's how to solve this ?
>>>>
>>>
>>>Bjorn,
>>>
>>>The WHERE clause of SELECT si applied to the source tables, there is no fild named WTG in the source fields. You can change it to;
>>>
>>>WHERE Detail.avr_wtg = "J"
>>>
>>
>>This will cause a data-type mismatch. If he's testing against the result of the iif(), he's got to use the HAVING clause.
>
>Naw, you don't need a HAVING or a comparison operator, simply

SELECT detail.avr_ari, "J" AS WTG;
>FROM general!detail;
>WHERE Detail.avr_wtg

will do the trick. Using Detail.avr_wtg = .T. slows things down.

George,

If you have index on avg_wtg (though it would be strange to have index on logical field), I assume, where avr_wtg=.t. should be faster than where avr_wtg

Correct me, please, if I'm wrong.