Newbie question on mysql_query bandwidth

[Link187]

is it better for me to do:

$result = mysql_query("SELECT * FROM subjects", $connection);

while($row = mysql_fetch_array($result){
//do something with the rows }

or should I only use mysql to ONLY get the rows that I need to use?

It seems a bit wasteful to get all of the fields/rows when I'm only going to using some of them but if it makes no difference to the server cpu or bandwidth and also if it's what most people (rightly) do then it's ok?

Please help.

[Link187]

Wow 58 views, no responses..Maybe it was a dumb question or maybe I wrote it wrong..I'll rephrase:

I know it depends on the context but is it ok to use

$result = mysql_query("SELECT * FROM subjects", $connection);

if I won't necessarily use all the rows that are returned.

I'll also wrap code tags around my previous post code..I forgot to do that last itme..sorry if it wasn't totally readable..

[MarkR]

Yep, it's always better to optimize your queries to only fetch info you'll actually use. SQL queries are likely to be the bottleneck in most systems.

Instead of using select *, only get columns you need. If you only need users registered after a certain date for example, only fetch those using a where clause in your SQL statement.