How do I know which record I'm reading from?

bunner_bob

I'm trying to build a javascript array from a set of retrieved records, using while(). The code looks like this:

echo "showPix = new Array(";
if ($randorder == 0) {
$result = mysql_query("SELECT FROM choushowimages WHERE showid=$showid ORDER BY sortorder", $db);
} elseif ($randorder == 1) {
$result = mysql_query("SELECT , rand() as r FROM choushowimages WHERE showid=$showid ORDER BY r", $db);
}

while ($myrow = mysql_fetch_array($result)) {
$filename = $myrow["filename"];
echo "\"images/slideshows/" . $showid . "/" . $filename . "\",";
}
echo ")\n";

The problem is, I end up with an extra comma, which makes the javascript malfunction. What I want to do is say something like:

while ($myrow = mysql_fetch_array($result)) {
$filename = $myrow["filename"];
if (this is the last record in the $result) {
echo "\"images/slideshows/" . $showid . "/" . $filename . ")"; // no comma and close parenthesis
} else {
echo "\"images/slideshows/" . $showid . "/" . $filename . "\","; // put in the comma
}

Bet this is easy, but it's outside my sphere o' knowledge...

pyfsapple

Just first get the number of rows in the result:

$result=......;
......
$total_num = mysql_num_rows($result);
for($i=1; $i< $result; $i++) {
    $filename = $myrow["filename"]; 
    echo "\"images/slideshows/" . $showid . "/" . $filename . "\",";
}
echo "\"images/slideshows/" . $showid . "/" . $filename . ")";

Get it? Note that $i should be started from "1", not "0".

Have a nice day!

pyfsapple

Sorry, the condition for the for-loop is not "$i < $result" but "$i < $total_num".

Have a nice day!

bunner_bob

Don't think that's it. First of all you're not applying the $i in the for loop anywhere. I would think it needs to be used in the first line in the for loop - something like "$myrow = the row of result numbered "$i"". Which brings us to number two - $myrow isn't defined.

I think there is something to this for loop idea, but it doesn't work just yet.

Is there a way, knowing how many records (rows) there are in a result, to specifically address one of those records by number?

cgraz

I just briefly skimmed over this post, but what you want to do is determine if this is the last record in the post? You should be able to get a count for the total number of rows. Then, set $i to 0 outside of the while loop. At the end of the while loop, you auto increment $i (add one to it). then within your while loop, if $i is equal to the number of results, then that is the last record. Something like this

$i = "0";
$rows = mysql_num_rows($result);

while ($myrow = mysql_fetch_array($result)) { 
   $filename = $myrow["filename"]; 
      if ($i == $rows) { // last record
         echo "\"images/slideshows/" . $showid . "/" . $filename . ")"; // no comma and close parenthesis 
      } else { 
         echo "\"images/slideshows/" . $showid . "/" . $filename . "\","; // put in the comma 
   } 

$i++;

}

Let me know how that works.

Cgraz

bunner_bob

Yeah man! That's the ticket.

One small mod - changed if($i == $rows) to if($i == ($rows - 1)) - since we're starting with $i = 0, it will always be 1 less than the number of rows (or I suppose I could make $i = 1...)

Also I put the $i++ inside the "else" statement - since I don't need to increment the counter once I reach the end of the result.

Thanks!

cgraz

Yeah, I was just going to come change $i=0 to $i=1. I was watching some tv and it hit me. 😉

Anyways, glad you got it working.

Cgraz

bunner_bob

I hate when the tv hits me.

Usually happens when it's been drinking...but that's no excuse.

😉

pyfsapple

Sorry I have missed this sentence:

$myrow = mysql_fetch_array($result);

inside the for-loop.

But it must be work with this statement:

$result=......;
......
$total_num = mysql_num_rows($result);
for($i=1; $i< $total_num; $i++) {
    $myrow = mysql_fetch_array($result);
    $filename = $myrow["filename"]; 
    echo "\"images/slideshows/" . $showid . "/" . $filename . "\",";
}
$myrow = mysql_fetch_array($result);
echo "\"images/slideshows/" . $showid . "/" . $filename . ")";

First of all, the $i is specify in the for() statement, don't you think that for-loop will use $i as the condition ($i<$total_num) ??
Secondly, this is better than use if-else inside while-loop!!

bunner_bob

Ahh - I get it. Thanks pyfsapple - I've got your version to work (though I think I need to add a $filename = $myrow['filename'] before the last line - right?)

Why is your way better than using if-else inside a while loop? Is there something bad about using if-else in a while loop?

pyfsapple

Right, I missed that~

That is, generally, with for-loop, the condition statement determination is faster than using if-else inside while-loop (pure while-loop is faster than for-loop, though). This is a matter of speed......
Thanks to the extremely high-speed processors nowadays, we don't really need to cosider the first point.

And I think this will be clearer to do something after for-loop (it means will be executed once) than that in the middle of while-loop, this make we confused if the statement will be executed more than one time.

The only bad point is you must do an extra copy-paste action in implementation, ha~

That are what I see~~