[SOLVED] MySQL UPDATE issue and a problem with fwrite().

[ZeroError]

It may seem odd that I have this combination, but it works best for me given that I'm still a beginner and am only just moving into MySQL. Anyhoo, here's my MySQL issue:

 

I created a simple script to increment the amount of cans I have (For an art project) in my inventory, and write that into a database. That database is then read on the homepage and printed to the screen as "I have <number> cans left, but I need <65 - number> more!". I have this code in the backend, which SHOULD allow me to update the number, but it just seems to stay at 6!

/* Before we do anything, we should connect to MySQL. */
mysql_connect("myserver", "db_user", "password") or die(mysql_error());
mysql_select_db("table_name") or die(mysql_error());

function incrementCans()
{
// Declare variables required for MySQL
$prevTotal 		= mysql_query("SELECT * FROM cans") or die(mysql_error());
$prevTotalRow 	= mysql_fetch_array( $prevTotal );
$updateTo		= $prevTotalRow['total'] + $_POST['amount'];

// Update can value
mysql_query("UPDATE cans SET total=".$updateTo." WHERE total=".$prevTotalRow['total']."") or die(mysql_error());

// Check database for updated table
$newTotal		= mysql_query("SELECT * FROM cans") or die(mysql_error());
$newTotalRow	= mysql_fetch_array( $newTotal );

echo("Total cans updated to " . $newTotalRow['total']);
}

 

I've changed nothing since it last worked (About a week ago) and no errors are given.

 

 

 

And now onto my second problem, with fwrite(). The script should check to see if a checkbox is ticked and write the contents of the corresponding textbox to the file, but I get the following message:

Warning: Wrong parameter count for fwrite() in /home/kittycat/public_html/admin/addline_all.php on line 140

 

My code goes like this:

133.    if (isset($_POST['maincheck']))
134.    	{
135.    	$file	= "../random/homebody.txt";
136.    	$handle	= fopen($file, 'a');
137.    	// checkFileOK_Write();
138.    	if (fopen($file, 'a'))
139.    		{
140.    		if (fwrite($handle))
141.    			{
142.    			echo ('Written \"' . $data . '\" successfully.');
143.    			fclose($handle);
144.    			}
145.    		else
146.    			{
147.    			echo ('Failure to write \"' . $data . '\".');
148.    			fclose($handle);
149.    			}
150.    		}
151.    	else
152.    		{
153.    		echo ('Failure to open \"' . $data . '\".');
154.    		}
155.    	}

Line 140 is

if (fwrite($handle))

in case my numbering didn't work.

 

Any input for either of these would be very useful, and much appreciated.

Thanks in advance!

[Alex]

If you check the manual you'll see that fwrite() takes 2 mandatory parameters: 1. The resouce ($handle in your case) which you are passing. 2. The data that you want to write to the file.

 

if(fwrite($handle, $data)) {...}

[ZeroError]

Oh, dear >.<

I can't believe I forgot the data to write :L

Thanks very much for that.

 

Still need help with the MySQL issue, though, most confusing.

[Alex]

put error_reporting(E_ALL); at the top of the page and see if any errors are thrown.

[ZeroError]

Thanks, I did that and it showed an undefined index on line 29. This was the $_POST variable for the amount of cans and was spelt wrong. Thanks for that, I'll be using that function a lot in the future.