RE: SQL statement performance question

["Keith McCully" <Keith.McCully@xxxxxxxxxxx>]

SELECT * FROM mytable will always be faster than SELECT A, B, C FROM mytable 
with all else being equal although, in practice, the difference may not be 
noticed. 

Basically the first statement is a reference to a set of rows from an existing 
table.
The second statement requires a new table to be built, even if mytable only 
contains fields A, B & C.

Keith
>-----Original Message-----
>From: java400-l-bounces@xxxxxxxxxxxx
>Subject: Re: SQL statement performance question
>
>My experience with SQL is that its completely unpredictable.  The only way
>to be 100% sure which query is faster on your iSeries configuration
>retrieving from that particular table is to write some code to run each
>query 100 or 1000 times and see which one is fastest, although in the case
>of just picking which fields you want from the same table I doubt you'll
>notice any difference.

>Nigel.

>-----Original Message-----
>Hi
>which SQL statement is more efficient

>SELECT * FROM mytable

>  OR
>SELECT A, B, C FROM mytable

>Why is it more efficient,
>If there are any articles about writing efficient SQL
>querries will really help


>Ashish