session variable check in mysql causing problems

[fohanlon]

Hi Guys

 

I have a mysql query that checks a table for a match for a userid and a sesion variable.  I store this when the user logs on and wipe it when they log out

 

Heres the issue.  When I then try to log in again it returns my message about already being logged in even though I would expect the mysq;l query to return 0 it always returns 1.

 

Heres the code:

 

$result = mysql_query("SELECT COUNT(*) FROM log_participants WHERE AccountID = '$accid' AND Course = '$course' AND SessionID = '" . mysql_real_escape_string(session_id()) . "'");

if(!$result) echo mysql_error();

echo "Result is " . mysql_num_rows($result);

 

Result is always 1.

 

Any ideas?

 

Thanks,

 

fergal.

 

 

[teng84]

yes result will be 1 why? because you will have this as your result

 

COUNT(*) = 0 ; 

so you have result one  result but the value of the rsult is 0

 

and rephrase your code kinda wrong though

[fohanlon]

So what you are saying it the COUNT(*) is 1 becuase the returned result is 0 i.e it is counting an empty result as 1.

 

How could I fix the code?

 

Thanks,

 

fergal.

 

[teng84]

replace count(*) with the specific fields your querying and use your Primary keys eg ID

 

so you have select field from tablename where etcc..

 

 

[fohanlon]

Thanks very much - that solved the problem.

 

Although i'd still like to know what count(*) was doing?  Must look at the man pages for php.

 

Fergal.