Count problem ?

MichaelHe

I am trying to count from a database, but it doesn't work as I want it to.

I have inserted these codes.

$sange = "SELECT count(*) as antalsange FROM Titler WHERE Pid='$brugerid'";
$count = mysql_query($sange);

Then later I write.

{IF ($count<$antal)...
{IF ($count>=$antal)....

$antal is in this case set to '3' and the entries mathing the SELECT is only '1' so it should run the first IF, but it runs the second one.
Sp somehow the count is more than 3...
Why doesn't it count it correct ??

Michael

laserlight

You forgot to use [man]mysql_result/man or [man]mysql_fetch_assoc/man

MichaelHe

OK..

I'm a little lost.. Hwo do I do that.
I have searches the PHP manual, but I can't figure out how to do it. ?

leatherback

$sange = "SELECT count(*) as antalsange FROM Titler WHERE Pid='$brugerid'";
$result = mysql_query($sange);
if($result)
{
$count = mysql_num_rows($result);
}

in the manual at http://www.php.net/mysql_num_rows. Don't tell us you searched

MichaelHe

OK now I got it... I rewrote it a little from the link you posted.
So now it lookes like this and it works.
Thank a lot

$result = mysql_query("select * from Tekster WHERE Pid='$brugerid'");
$count = mysql_num_rows($result);

It's a little difficult for newbies to search the manaul, since we don't know the name of the commands.

I searched for Count, and couldn't find examples where they counted from a database.
Since I didn't know the command mysql_num_rows I didn't know what else to search for than Count.

leatherback

Hi,

OK, I was a bit quick with that one ;-)

You have removed the if statement which I placed. You do need it though. If you do not place it, you getlots of errors if the query is wrong. Also, place a little line: or die('Some query trouble: 'mysql_error()); behind the query statements:

$result = mysql_query("select * from Tekster WHERE Pid='$brugerid'") or die('Some query trouble: 'mysql_error());

This will help you to debug quite a bit

Happy PhP-ing!

MichaelHe

It's funny you say that.
I have often wondered why there are always or die commands, and others that do something if the query is wrong.

How can the query be wrong ??
I mean, I have a database with the data in. In the database Tekster there are a field called Pid with a number in.
With the statement - Tekster WHERE Pid='$brugerid'") - there will always be an output. Pid always contains a number and $brugerid is tranfered to the site in a link, so it will also always have a number.
So how can there be any errors ??

laserlight

Here your only intention is to obtain the numberof rows. There's no need to select all the rows and then use mysql_num_rows(). Your original SQL statement is correct, just that $count contains the result resource instead of the actual count.

leatherback's example is incorrect since it uses mysql_num_rows() on the SELECT COUNT(*) query, so it should always return 1.

$query = "SELECT COUNT(*) AS antalsange FROM Titler WHERE Pid='$brugerid'";
$result = mysql_query($query)
	OR die(mysql_error()); //for debugging
$count = mysql_result($result, 0);

I have often wondered why there are always or die commands, and others that do something if the query is wrong.

Using die() or exit() usually isnt a particularly graceful way to react to an error, but for tests and examples it usually suffices.

leatherback

Well, in tons of ways.

Primarily: you could have made a typo in the script (So when buidling / debugging)

but also:
- There might be a problem with the database
- Somebody may have tinckered with the input from forms
- The query can be generated on the fly, based on selection => trailing comma's etcetc, again: Mainly during dev.

All in all.. It is always good to have something handle the potential problems, I think.

MichaelHe

So mainly it's under developement it's a good idea..

I have thought of the 'tinckered with the input from forms'

I have a song table with a user id field (Pid). This user id is the id of the user that have access to this song.
Then I have a users table containing Userid, username and password.

I transfer songid from the song table and the username and password from the users tabel, and collect these 3 and the Pid (the userid on the user that have access to this song) from the song table.
And then I find the userid in the users table based on the username and password.
At last I check if the userid found in the users tabel is the same as the Pid in the song table, on the song they which to update.
This way you can't change the songid, username or password tranfered from the form, since the Pid on that chosen song then wouldn't be the same as the userid found by the username and password in the users table.

In short, the song id tranfered from the form has to matched the username and password fransfered from the form. So if you do not know the username and password on the user that have access to songid 8, then you can't update songid 8.