In the query #2 from wich record do you expect result value for Descript would come from for each group? SQL Engine does not have this info and cannot proceed.

The question of 'which record' is answered by the WHERE clause, is it not? I always thought GROUP BY determined the physical order of the records in the result set, not which records are returned.

So in your example #2, since, you said 'ORDER BY Code', then record #1 would be first, then record #2, based off the values in the code field.

I don't see what I'm missing.


>

>Table: mytable
>Code Descript Qty
>  1  One      110
>  1  OneOne   120
>  2  Two      210
>  2  Two      220
>
>-- #1
>SELECT Code, SUM(Qty) FROM mytable GROUP BY Code
>Result
>Code Qty
>  1  230
>  2  430
>
>-- #2
>SELECT Code, Descript, SUM(Qty) FROM mytable GROUP BY Code
>Result
>Code Descript  Qty
>  1  ?         230
>  2  ?         430
>

>
>>
>>"....than SQL engine wouldn't know what record it should come from"
>>
>>Huh?? I don't get this.