Help building / using array

Posted on 16th Feb 2014 by admin

First - this is a cross-posting, if this is wrong I apologise! What started out as a MySQL query question (original post http://www.phpfreaks.com/forums/index.php/topic,273323.0.html) has become a PHP coding question....

I have 2 tables - docs and doc_relationships: -

+-------------+--------------+---Table: docs-----+-----------+---------------------+---------+
| document_id | doctype | location | title | thumbnail | added | visible |
+-------------+--------------+-----------+-------+-----------+---------------------+---------+
| 1 | instructions | pdf/a.pdf | a | img/a.jpg | 2001-04-12 20:16:58 | Y |
+-------------+--------------+-----------+-------+-----------+---------------------+---------+
| 2 | pressrelease | pdf/b.pdf | b | img/b.jpg | 2002-04-09 20:18:33 | Y |
+-------------+--------------+-----------+-------+-----------+---------------------+---------+
| 3 | newsletter | pdf/c.pdf | c | img/c.jpg | 2003-05-21 11:18:54 | Y |
+-------------+--------------+-----------+-------+-----------+---------------------+---------+
| 4 | instructions | pdf/x.pdf | x | img/x.jpg | 2004-01-22 19:13:21 | Y |
+-------------+--------------+-----------+-------+-----------+---------------------+---------+
| 5 | pressrelease | pdf/y.pdf | y | img/y.jpg | 2005-02-17 17:11:17 | Y |
+-------------+--------------+-----------+-------+-----------+---------------------+---------+
| 6 | instructions | pdf/z.pdf | z | img/z.jpg | 2006-07-02 12:15:58 | Y |
+-------------+--------------+-----------+-------+-----------+---------------------+---------+
| 7 | pressrelease | pdf/p.pdf | p | img/p.jpg | 2002-03-01 18:31:26 | Y |
+-------------+--------------+-----------+-------+-----------+---------------------+---------+


+-------Table: doc_relationships-----+
| rel_id | document_id | product_id |
+--------+--------------+------------+
| 1 | 1 | 4 |
+--------+--------------+------------+
| 2 | 2 | 3 |
+--------+--------------+------------+
| 3 | 4 | 3 |
+--------+--------------+------------+
| 4 | 6 | 2 |
+--------+--------------+------------+
| 5 | 7 | 3 |
+--------+--------------+------------+

Each row in the doc_relationships table ties one document to a product_id (product_ids are held in another table and will be hardcoded), the above example gives: -

doc 1: instructions, product 4
doc 2: pressrelease, product 3
doc 3: newsletter
doc 4: instructions, product 3
doc 5: pressrelease
doc 6: instructions, product 2
doc 7: pressrelease, product 3

Each product can have any number of Instructions, Press Releases and Newsletters related to it.
Press Releases and Newsletters can be related to one or more product.
Instruction manuals are usually related to one product only.

So far I have three pages - newsletters, pressreleases and instructions, which simply list all the matching documents, using this query: -

Code: $query="SELECT * FROM docs WHERE doctype='newsletter' AND visible='Y' ORDER BY added DESC, document_id DESC";

The problem is I also want to list any relevant documents on product pages, under headings referrring to doc types, so for example on product 3's page: -

-----------------------------------------------------------------------------------------
Product #3 - Super Widget

Desription - this is a remarkable widget, you'll wonder how you ever managed without one!

Instructions:
(link to doc 4)

Press Releases: -
(link to doc 2)
(link to doc 7)
-----------------------------------------------------------------------------------------

The query I'm using for the product pages is as follows: -

Code:
$query="SELECT * FROM docs, doc_relationships WHERE doc_relationships.document_id=docs.document_id AND doc_relationships.product_id='3' AND visible='Y' ORDER BY docs.added DESC, docs.document_id DESC";


I could add another condition to this query for "doctype" and do it 3 times, once for each doctype, but ideally what I'd like to do on a product page is create 3 arrays (newsletters, pressreleases & instructions) containing the details of each for that product (if any). So here's what I have so far: -

Code: // connect to database and issue the query
mysql_connect($server,$dbusername,$dbpassword);
@mysql_select_db($db_name) or die( "Unable to select database");
$query="SELECT * FROM docs, doc_relationships WHERE doc_relationships.document_id=docs.document_id AND doc_relationships.product_id='3' AND visible='Y' ORDER BY docs.added DESC, docs.document_id DESC";
$all_documents=mysql_query($query);
$total_docs=mysql_num_rows($all_documents);
mysql_close();

if ($total_docs != 0) {
while ($sql = mysql_fetch_object($all_documents)) {
if ($sql -> doctype=='newsletter'){
echo 'document #' . $sql -> document_id . ' is a newsletter<br />';
// create the newsletters array if it doesnt exist
if (!is_array($newsletters)) $newsletters= array();
// add to newsletters array;
array_push($newsletters, $sql);
} else if ($sql -> doctype=='pressrelease'){
echo 'document #' . $sql -> document_id . ' is a pressrelease<br />';
// create the pressreleases array if it doesnt exist
if (!is_array($pressreleases)) $pressreleases= array();
// add to pressreleases array;
array_push($pressreleases, $sql);
} else if ($sql -> doctype=='instructions'){
echo 'document #' . $sql -> document_id . ' is instructions<br />';
// create the instructions array if it doesnt exist
if (!is_array($instructions)) $instructions array();
// add to instructions array;
// not quite sure how!
array_push($instructions, $sql);
}
}
}

print_r($instructions);

As you can see, I added some test echos and this works as expected. The result of the final print_r($instructions) command is: -

QuoteArray ( => stdClass Object ( [document_id] => 4 [doctype] => instructions [location] => pdf/x.pdf [title] => x [thumbnail] => img/x.jpg [added] => 2004-01-22 19:13:21 [visible] => Y [rel_id] => 3 [product_id] => 3 ) ) The problem is I can't seem to extract the data from this array individually, for example I thought: -

Code: echo $instructions[0]['document_id'];

would echo '4' but it doesn't (and actually stops the page output dead).

So: -

1) Am I inserting results into the arrays correctly?

2) How do I access individual document info from each array?

3) How do I (for each array) loop through all documents?