Accessing second table within a while loop - php

Question

forgive me I just learned php this week, so I'm not sure I'm doing this all right.
It starts out accessing the DB, and the categories table for headers; it then takes that info and creates the header, pricing, and catalog links.
Then within that while loop after it completes the first part it's supposed to run a second while loop to access the products table to list all the products with the category_id that matches the cat_id from the categories table.
When it prints out it should be
Header
Pricing PDF
Item Dimensions Image Image
Item Dimensions Image Image
Item Dimensions Image Image
etc
Header
Pricing PDF
Item Dimensions Image Image
etc....
And so far the first while loop works but the second isn't. Is there a correct way to pass the variable? Can I just not access a second table while in a while loop for the first table? I dunno...I've tried a few things, and nothing is working well
<?php
//connect to server
$con = mysql_connect('localhost','username','password');
//test connection
if (!$con)
{
die ('Could not connect: ' . mysql_error());
}
//access primary DB
mysql_select_db("main_db", $con);
//place table into variable
$categories = mysql_query("SELECT * FROM categories");
//begin table build
while($row = mysql_fetch_array($categories))
{
//set shading variable
$table_row = 0;
//set current set
$cur_set = $row['cat_id'];
//create document link and header
echo "<a name='" . $row['cat_name'] . "'><h3>" . $row['cat_title'] . "</h3></a>";
//create table and table formatting cell
echo "<table id='productTable'><tr id='tableHead'>";
//table width formattting here
echo "<td style='width:165px;'></td>";
echo "<td style='width:235px;'></td>";
echo "<td style='width:155px;'>";
//link and icons to category catalog
echo "<a href='catalog/" . $row['cat_pdf'] . ".pdf'><img src='data/pdflogo.png' alt='pdf button' /></a>";
//link and icons to category pricing sheet
echo "<a href='catalog/" . $row['cat_pricing'] . ".pdf'><img src='data/pricinglogo.png' alt='pricing button' /></a>";
//finish formatting
echo "</td></tr>";
//place table into variable
$products = mysql_query("SELECT * FROM products WHERE category_id='" . $row['cat_id'] . "'");
//begin table build
while($table = mysql_fetch_array($products));
{
//create up row
echo "<tr id='tr" . $table_row . "'>";
//create first cell
echo "<td>" . $table['prod_name'] . "</td>";
//create second cell
echo "<td>" . $table['prod_dim'] . "</td>";
//create third cell
echo "<td>";
//create third cell, first image
echo "<a href='catalog/" . $table['prod_img1'] . ".jpg'>" . "<img src='data/jpglogo.png' alt='image button' />" . "</a>";
//create third cell, second image
echo "<a href='catalog/" . $row2['prod_img2'] . ".jpg'>" . "<img src='data/jpglogo.png' alt='image button' />" . "</a>";
//finish formatting
echo "</td></tr>";
//cycle row
if ($table_row == 0)
{
$table_row = 1;
}
else
{
$table_row = 0;
}
//end table
echo "</table>";
}
}
//close connection
mysql_close($con);
?>
Thanks in advance

Answer 1

It would be more streamlined to perform an INNER JOIN on both tables
SELECT
A.cat_id,A.cat_name,A.cat_title,A.cat_pdf,A.cat_pricing,
B.prod_name,B.prod_img1,B.prod_img2
FROM categories A INNER JOIN products B ON A.cat_id = B.category_id;
You can iterate on A.cat_id
This is my proposed suggestion (braces might be off, but here is what the iteration on cat_id should look like). Please change the style for starting and stopping tags.
<?php
//connect to server
$con = mysql_connect('localhost','username','password');
//test connection
if (!$con)
{
die ('Could not connect: ' . mysql_error());
}
//access primary DB
mysql_select_db("main_db", $con);
//place table into variable
$categories = mysql_query("SELECT A.cat_id,A.cat_name,A.cat_title,A.cat_pdf,A.cat_pricing,B.prod_name,B.prod_img1,B.prod_img2 FROM categories A INNER JOIN products B ON A.cat_id = B.category_id");
$current_catid = -1;
//begin table build
while($row = mysql_fetch_array($categories))
{
if ( $current_catid != $row['cat_id'] )
{
if ( $current_catid > -1 ) { echo "</table>"; }
$current_catid != $row['cat_id']
//set shading variable
$table_row = 0;
//set current set
$cur_set = $row['cat_id'];
//create document link and header
echo "<a name='" . $row['cat_name'] . "'><h3>" . $row['cat_title'] . "</h3></a>";
//create table and table formatting cell
echo "<table id='productTable'><tr id='tableHead'>";
//table width formattting here
echo "<td style='width:165px;'></td>";
echo "<td style='width:235px;'></td>";
echo "<td style='width:155px;'>";
//link and icons to category catalog
echo "<a href='catalog/" . $row['cat_pdf'] . ".pdf'><img src='data/pdflogo.png' alt='pdf button' /></a>";
//link and icons to category pricing sheet
echo "<a href='catalog/" . $row['cat_pricing'] . ".pdf'><img src='data/pricinglogo.png' alt='pricing button' /></a>";
//finish formatting
echo "</td></tr>";
}
//create up row
echo "<tr id='tr" . $table_row . "'>";
//create first cell
echo "<td>" . $table['prod_name'] . "</td>";
//create second cell
echo "<td>" . $table['prod_dim'] . "</td>";
//create third cell
echo "<td>";
//create third cell, first image
echo "<a href='catalog/" . $table['prod_img1'] . ".jpg'>" . "<img src='data/jpglogo.png' alt='image button' />" . "</a>";
//create third cell, second image
echo "<a href='catalog/" . $row2['prod_img2'] . ".jpg'>" . "<img src='data/jpglogo.png' alt='image button' />" . "</a>";
//finish formatting
echo "</td></tr>";
//cycle row
if ($table_row == 0)
{
$table_row = 1;
}
else
{
$table_row = 0;
}
//end table (Fix this, might produce extra table tag)
echo "</table>";
}
//close connection
mysql_close($con);
?>

Answer 2

You are loading relative data, so a short answer is no, because of the overhead you will probably have if you would select them with joins.
Also, try to limit the overhead created by the * by selecting only what you want and not everything.
Also follow Truth's recommendations, for new mysql(i) calls. Once you get a hang with sql and php, you can move to other types of database calls (using object oriented code -- or activerecord), but please try to understand how mysql calls are being done first.