test condition for if statement

seanisean

Hi i'm just looking for a little help with this one.....

i have a thumbnail index which displays all the images as links which you can click on and look at a larger sized version of each image, below the large image is a "<< prevoius","back to thumbs" and a "next >>" link the "<<previous" is easy to stop from displaying when there are no images less than 1, but i'm struggling stopping the "next >>" link showing when there are no more images to that particular thumbnail group the code is here:

<?php
				$previous=$picture_id-1;
				$next=$picture_id+1;
				if($previous<1)
				{
					echo("..........");
				}
				else
				{
					echo("<a href=\"projectfullsize.php?id=$previous&prjct=$project_id\"><<  previous</a>");
				}
					echo("&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;");
					echo("<a href=\"projectthumbs.php?id=$project_id&prjct=$project_id\">back to thumbnails</a>");
					echo("&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;");
				if(!mysql_query("SELECT * FROM projects WHERE project_number = '$project_id' AND picture_number = '$next'"))
				{
					echo("..........");
				}
				else
				{
					echo("<a href=\"projectfullsize.php?id=$next&prjct=$project_id\">next  >></a>");
				}

		?>

the problem is with the condition:

if(!mysql_query("SELECT * FROM projects WHERE project_number = '$project_id' AND picture_number = '$next'"))

the database feilds have a group id and a picture id so group 1
will have images 1 to 9, and group 2 will have images 1 to 12, so i guess im looking for the correct test condition to check that if image 13 doesnt exist in group 2 that when displaying image 12 instead of the "next >>" link displaying it echos the "........." instead,

thanks in advance to anybody helping

regards

sean

konsu

i suppose that you expect the query to return zero rows in which case you do not display the next link. is that so? if so, even though the query returns zero rows in its resultset, it still is considered a successfull query, so your test in the if statement will always fail. you need to check for both success of the query and number of rows.

seanisean

perhaps if i give this link it will explain it better than my previous babbling🙂

http://www.landscape-service.com/development/projectthumbs.php?id=1

if you click the first image... below there is no "<< previous link"
as i have tested that the link must be greater than 0.

but if you click on the last image or the ninth image the "next >>" link still shows😕

so because each group of images could be 9 or 12 or whatever i need a way to test for the last image of a group.

as i said before i have group_id and picture_id feilds in the database so i am trying to test for the last image in a group ie: project 1 image 9 so if project 1 image 10 doesnt exist what would be the test condition for that.

regards

sean

konsu

in sql terms, if the below query returns zero rows then you do not need to show the next link, right?

SELECT * FROM projects WHERE project_number = '$project_id' AND picture_number = '$next'

seanisean

ok I see where your coming from so i just tried this instead

if(mysql_query("SELECT * FROM projects WHERE project_number = '$project_id' AND picture_number = '$next'")==0)
				{
					echo("..........");
				}
				else
				{
					echo("<a href=\"projectfullsize.php?id=$next&prjct=$project_id\">next  >></a>");
				}

and it still shows the "next >>" link on the final picture, so now i'm thinking my semantics are way off here??

cheers for your help by the way Konsu

regards

sean

konsu

there is a php function that i do not remember the name of that you need to use on the resultset returned by mysql_query() to test for the number of rows. something like number_of_rows() or row_count(). php.net should have it.

oh, here it is: http://us2.php.net/manual/en/function.mysql-num-rows.php

seanisean

Thanks alot for your help Konsu, you got me on the right track!

i used this code:

$result = mysql_query("SELECT * FROM projects WHERE project_number = '$project_id' AND picture_number = '$next'");
$row_number = mysql_num_rows($result);
if($row_number==0)
{
	echo("..........");
}
else
{
	echo("<a href=\"projectfullsize.php?id=$next&prjct=$project_id\">next  >></a>");
}

all now works as wanted you've been a great help

cheers again

sean