which query is quickest.....

to count number of users in my database

do a mysql COUNT(id) on my table.

or select id, and do mysql_num_rows

which of those two will execute the fastest?

The first COUNT(id) will execute faster because no result set has to be transfered.

count(*) should be even faster - a well optimized DB backend will only count rows.

(Technically, the two are slightly different: count(id) only counts unique, non-null IDs - which shouldn't be an issue for a typical artificial primary key row, of course.)

Take it easy,

Dave

Look up the BENCHMARK() mysql command. This will help you.

The first COUNT(id) will execute faster because no result set has to be transfered.

only true for myisam.

for innodb, if i'm not wrong, the speed of select count(id) is almost the same as the speed of select id

thanks for the help guys :)