php - comparing resultsets

[toString]

Having yet more php troubles (it never seems to end)...

while ($row = mysql_fetch_row($rs_full)) {
	while ($row2 = mysql_fetch_row($rs_selected)) {
		if ($row[0] == $row2[0]) {
			echo "$row2[1]";
		}	
	}
}

Should something like that work? I'm finding it doesn't, at all. Am I doing something wrong? It *looks* right, (to me at least)..

$rs_selected is a subset of $rs_full.

 

[toString]

No ideas php gods?

I'll tell you what does happen, it cycles through all 30 of $rs_full.
But it will only print out the first result from $rs_selected and that's it. It never prints out the 2nd, 3rd, etc. Even though there is a few more results.

It'd be alright if I could see something wrong, I could then work out how to fix it, but I don't know what is wrong which makes it frustrating

 

[Augmented]

Would it not be better to do this comparison within your MySQL query, and save you all the trouble and overhead of doing it with PHP?

SELECT from table1, table2 WHERE table1.row = table2.row

for example.

 

[toString]

Sounds like an idea, but I'm not sure if it's possible with my queries:

$full_q = "SELECT CatID, CatName FROM category";
$rs_full = mysql_query($full_q);

$selected_q = "SELECT CatID, CatName
	FROM category
	WHERE CatID IN (SELECT CatID FROM product_category WHERE ProductID=".getInput($_GET['id']).")";
$rs_selected = mysql_query($selected_q);

I need the full listing of categories, but at the same time I need to know which of these categories are selected in the 'product_category' table.

 

[LazyManc]

Having yet more php troubles (it never seems to end)...

while ($row = mysql_fetch_row($rs_full)) {
	while ($row2 = mysql_fetch_row($rs_selected)) {
		if ($row[0] == $row2[0]) {
			echo "$row2[1]";
		}	
	}
}

Should something like that work? I'm finding it doesn't, at all. Am I doing something wrong? It *looks* right, (to me at least)..

$rs_selected is a subset of $rs_full.

You're not incrementing any counter, you're just statically comparing $row[0] against $row2[0]...

Try

$i = 0;
while ($row = mysql_fetch_row($rs_full)) {
$j = 0;
	while ($row2 = mysql_fetch_row($rs_selected)) {
		if ($row[$i] == $row2[$j]) {
			echo "$row2[$j+1]";
		}
		$j++;
	}
	$i++;
}

 

[toString]

Perfect! Thanks guys, got it all sorted now