Re: Fastest way to get table records' number

Hi, did you try mysql_num_rows ? --- Andrew Ballard <aballard@gmail.com> wrote: > On Wed, Mar 19, 2008 at 1:04 PM, TG > <tg-php@gryffyndevelopment.com> wrote: > > > > It seems that count(*) pulls all the data from > the row then performs a count > > increment whereas count(did) only pulls the 'did' > column. > > Again, I don't believe COUNT(*) pulls any data. If > there is a row, it > simply counts it. The row could be full of NULLS (if > allowed by your > schema - yikes) and it will still be counted. I'd > guess that COUNT(1) > does the same thing. COUNT(did) does only examine > the did column, > but NULL values are excluded from the count. > > > I wonder if count(did) is the same speed as > count(1) or if it will depend on > > how much/what type of data is in 'did'. > > > > > > I also wonder why count() takes a parameter. > Isn't it always going to count > > +1 for the row? I'll have to look that up > sometime. > > It takes a parameter because it depends on what you > want to count. > COUNT(*) will return the number of rows matching the > WHERE clause. > COUNT(column_name) will return the number of > non-NULL values in the > column column_name. You could have a million rows > in the table, but > if every row has NULL in column_name, the COUNT() > will return 0. > There is also COUNT(DISTINCT column_name), which > counts the number > of distinct, non-NULL values in the column. > > Andrew > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs