Not pulling up right row count

Sonic_Rage

I'm trying to simply get a row count of how many images are in my database, I know there is roughly 320 or so, but my query keeps saying I have only 1. What am I doing wrong here? 😕

$query = "SELECT COUNT(*) from rpg_images";
$result = @($query);
$num_images = @mysql_num_rows($result);

echo "<P>There are ".$num_images." images in the database.";

:mad:

diego25

Let's trace your program:

$query = "SELECT COUNT(*) from rpg_images";
$result = @($query);

RESULT:
A table like the following:

| COUNT(*) |
|--------------|
| 320 |
|--------------|

$num_images = @mysql_num_rows($result);

RESULT:
counts the number of rows of the resultant table. The table only had 1 row with number 320, so it returns 1.

I'm sure you can figure out what you did wrong from here...

Diego

Sonic_Rage

Thanks, so I tried this:

$query = "SELECT from rpg_images";
$result = @($query);
$num_images = @mysql_num_rows($result);

echo "<P>There are ".$num_images." images in the database.";

and now it returns the correct number. I guess I got confused by using the COUNT() .

Thanks for your help. :o

Weedpacket

Use the COUNT - that's what it's there for.

$query = "SELECT COUNT(*) from rpg_images";
$result = mysql_query($query);
list($num_images) = mysql_fetch_row($result);

Sonic_Rage

Ok, I know this might sound stupid, but what is the benefit of me using:

$query = "SELECT COUNT(*) from rpg_images";
$result = mysql_query($query);
list($num_images) = mysql_fetch_row($result);

compared to this:

$query = "SELECT * from rpg_images"; 
$result = @mysql_query($query); 
$num_images = @mysql_num_rows($result);

when I get the same results? I would just like to better understand the concept 😃

Weedpacket

Originally posted by Sonic_Rage
Ok, I know this might sound stupid, but what is the benefit of me using this comapared to this

Basically it's a matter of using the right tool for the job (in this case, MySQL instead of PHP).

In the second piece of code, all the data in the entire table is taken out of MySQL, piped to PHP and converted into a recordset (taking up who knows how much memory), and then the number of rows in that recordset is counted.

In the first piece, MySQL sends a single row, containing one field containing one number - a number which it is already keeping track of for its own purposes anyway. So for MySQL, the number of rows in the table is immediately to hand - and if MySQL already knows the number, it seems a bit redundant to have PHP calculate it all over again. But the big savings are in PHP's memory and loading on the communication between MySQL and PHP.

In short, getting MySQL to do the counting entails far less work is involved for both MySQL, PHP, and less has to be communicated between them. So everything runs faster and uses fewer resources and everyone's happy 🙂

Sonic_Rage

Oh ok, that makes sense. Especially when your database contains many rows. Thank you for clearing that up for me, makes perfect sense. 😃