what takes the less resources

[Anonymous]

I'm rewriting a whole website...and now I came a cross a little piece that I have to verify if a username already exists or not. The website has got more than 25000 members...what takes less resources:

to just select 'em all in one query or to only select the ones that start with the first letter of the username in question? (e.g. a%)?

Does anyone know how I could test these things? How to find out how much cpu power/memory it uses It's a massive website so it's really important that it uses as less possible

 

[Anonymous]

$query = 'select username from users where username = "'.$username"';
$result = mysql_query($query);
if(mysql_num_rows($result))
{
echo 'User Exists';
}
else
{
//add user code goes here
}

 

[Anonymous]

oh yeah...hmm stupid very very ah well, it was late thx mate

but what is the function to show how many milliseconds it takes to parse the script?

 

[Anonymous]

so it's microtime() thanks alot! For some reason I couldn't find it anywhere on php thanks!

 

[Anonymous]

you could just make mysql do the hard work and set the username field to UNIQUE - that way, trying to insert a new row fails and you can output an error. Saves having to do any select before the insert = less queries = good.