counting number of unique entries under a column

[mr_burns]

hi,
i am wanting to count the number of unique rows under a certain
column. i want to count how many times a page has been accessed. how i
plan to do this is every time a page is accessed, a session id
variable is checked for. if noe exist, a piece of code will create on.
then the session id is store in a table under one column and the pages
pre-defined number will be stored under another. so if i want to check
how many users have access a page in seperate sessions, all i need to
do is count how many unique session ids exist for that page (using the
page number - i.e. SELECT ... WHERE page_id = 8).

as i mentioned, i dont know how to count how many unique entries their
are under a column. any ideas??

also, how is it i check if a variable exists??

cheers

burnsy

[Tom Thackrey]

Re: counting number of unique entries under a column


On 8-Oct-2003, bissatch@yahoo. co.uk (mr_burns) wrote:
[color=blue]
> i am wanting to count the number of unique rows under a certain
> column. i want to count how many times a page has been accessed. how i
> plan to do this is every time a page is accessed, a session id
> variable is checked for. if noe exist, a piece of code will create on.
> then the session id is store in a table under one column and the pages
> pre-defined number will be stored under another. so if i want to check
> how many users have access a page in seperate sessions, all i need to
> do is count how many unique session ids exist for that page (using the
> page number - i.e. SELECT ... WHERE page_id = 8).
>
> as i mentioned, i dont know how to count how many unique entries their
> are under a column. any ideas??[/color]

assuming mysql:
$rs = mysql_query("se lect distinct columnname from tablename where
page_id=8") or die(mysql_error ());
$num_rows = mysql_num_rows( $rs);
[color=blue]
>
> also, how is it i check if a variable exists??[/color]

if (isset($variabl ename))
// $variablename exists
else
// it doesn't

--
Tom Thackrey

https://www.creative-light.com

tom (at) creative (dash) light (dot) com
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[Andy Hassall]

Re: counting number of unique entries under a column

On 8 Oct 2003 17:09:48 -0700, bissatch@yahoo. co.uk (mr_burns) wrote:
[color=blue]
>i am wanting to count the number of unique rows under a certain
>column. i want to count how many times a page has been accessed. how i
>plan to do this is every time a page is accessed, a session id
>variable is checked for. if noe exist, a piece of code will create on.
>then the session id is store in a table under one column and the pages
>pre-defined number will be stored under another. so if i want to check
>how many users have access a page in seperate sessions, all i need to
>do is count how many unique session ids exist for that page (using the
>page number - i.e. SELECT ... WHERE page_id = 8).
>
>as i mentioned, i dont know how to count how many unique entries their
>are under a column. any ideas??[/color]

SELECT COUNT(DISTINCT whatever)
FROM ...
[color=blue]
>also, how is it i check if a variable exists??[/color]

http://www.google.com/search?q=if+a+variable+exists+site:www.php.net&l=en

--
Andy Hassall (andy@andyh.co. uk) icq(5747695) (http://www.andyh.co.uk)
Space: disk usage analysis tool (http://www.andyhsoftware.co.uk/space)