[RESOLVED] Multidimensional Arrays

TrickyPhillips

I've been reading up on multidimensional arrays, and all the examples I've been seeing have a pre-determined number of x/y elements... What I want to do is more along the lines of C++ usage, with something like this:

for($i = 1; $i <= 32; $i++)
{
	$result = mysql_query("SELECT * FROM items WHERE category = " . $i);
	while($row = mysql_fetch_array($result))
	{
	$itemname[$i][$row]  = $row['itemname'];
	$itemprice[$i][$row] = $row['itemprice'];
	$counter++;
	}
}

When I try running that as it is, it gives me an error about "Illegal offset type." I assume it wants the array structure to be defined first. How can I define a structure like this, without first knowing the number of elements it will contain?

laserlight

$row is an array, but you are attempting to use it as an index. I suspect you just want to write:

$itemname[$i][]  = $row;

EDIT:
Sorry, my above solution is not quite what you asked for. However, upon some reflection, I think you should try something along these lines:

$result = mysql_query("SELECT category, itemname, itemprice FROM items WHERE category BETWEEN 1 AND 32");
$itemname = array();
$itemprice = array();
while ($row = mysql_fetch_assoc($result))
{
    $itemname[$row['category']][] = $row['itemname'];
    $itemprice[$row['category']][] = $row['itemprice'];
}

TrickyPhillips

laserlight wrote:
$row is an array, but you are attempting to use it as an index. I suspect you just want to write:
$itemname[$i][]  = $row;
EDIT:
Sorry, my above solution is not quite what you asked for. However, upon some reflection, I think you should try something along these lines:
$result = mysql_query("SELECT category, itemname, itemprice FROM items WHERE category BETWEEN 1 AND 32");
$itemname = array();
$itemprice = array();
while ($row = mysql_fetch_assoc($result))
{
    $itemname[$row['category']][] = $row['itemname'];
    $itemprice[$row['category']][] = $row['itemprice'];
}

Thank you for your suggestions. It seems I was treating $row very incorrectly. Haha. I guess that was the real problem.

I've played around with my script a bit, and it seems to be working as it should be now. I'm heading to class, but I'll fiddle with it some more later.

Thanks laserlight!

laserlight

I've played around with my script a bit, and it seems to be working as it should be now. I'm heading to class, but I'll fiddle with it some more later.

That's good. Note that your original version had 32 SQL queries but my suggestion only has one, which is much better.

Also, consider using the MySQLi extension or PDO extension instead of the MySQL extension.

TrickyPhillips

laserlight wrote:
That's good. Note that your original version had 32 SQL queries but my suggestion only has one, which is much better.

That's a good point... especially considering my table has about 125,000 rows. Thanks for that!

laserlight wrote:
Also, consider using the MySQLi extension or PDO extension instead of the MySQL extension.

I can't say I know much about these. What would be the benefits of switching?

laserlight

I can't say I know much about these.

MySQLi extension
PDO extension

What would be the benefits of switching?

Both extensions provide an object based interface (with an optional procedural interface). The MySQLi extension allows you to use features available since MySQL 4.1. The PDO extension allows you to use the same database interface in PHP across different database management systems. Both have support for prepared statements, which can come in handy as a way to escape input and for running the same SQL statement with different values.

TrickyPhillips

laserlight wrote:
MySQLi extension
PDO extension

Both extensions provide an object based interface (with an optional procedural interface). The MySQLi extension allows you to use features available since MySQL 4.1. The PDO extension allows you to use the same database interface in PHP across different database management systems. Both have support for prepared statements, which can come in handy as a way to escape input and for running the same SQL statement with different values.

Sounds good. Thanks for all the help! I really appreciate it.

laserlight

You're welcome 🙂
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