There is a performance issue to consider, for example you may have a 100
columns but only actually use say 15 of them. Thus you are sending more
data over the wire than you actually need, on top of that there is caching
and indexing to consider which will also degrade performance.

For the database to know what columns are there, and since you're not
giving your database any hints as to what you want, it will first need to
check the table's definition in order to determine the columns on that
table. That lookup will cost some time - not much in a single query - but
it adds up over time

This is only a small snippet of the problem, and you would need to
understand how databases works to fully understand the problem.


-- 
Regards,
Andrew Scott
WebSite: http://www.andyscott.id.au/
Google+: 
http://plus.google.com/113032480415921517411<http://plus.google.com/108193156965451149543>



On Tue, Aug 14, 2012 at 9:54 AM, Rob Voyle <[email protected]> wrote:

>
> Hi Folks
>
> several commented that select * is not good practice.
> The tables I have are relatively small approx 40 columns and I use all of
> the
> them.
> is there a risk in using the select *
>
> Thanks
> Rob
>
>
> 

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