Not displaying data from mysql - php

Question

I have this table,
--------------------------------------------
| products_id | related_products_ids |
| -----------------------------------------
| 1 | 1,2,3,4,6, |
| -----------------------------------------
| 2 | 1,2,3, |
| -----------------------------------------
| 3 | 1,2, |
-------------------------------------------
I want to display those related products in the product page. How can I do that?
Example, I'm in the product page where products_id is 1, i want to display the products from a table like table_name1 by related_products_ids.
I have used this code for displaying data,
$sql = "SELECT related_products_ids FROM ".TABLE_RELATED_PRODUCTS." where products_id = '" . (int)$_GET["products_id"]."'";
$result = mysql_query($sql);
$row = mysql_fetch_array($result);
$lst_rp = explode(',', $row['related_products_ids']);
echo '<ul>';
foreach($lst_rp as $rp_id) {
$res = "SELECT products_id, products_name FROM ".TABLE_PRODUCTS_DESCRIPTION." WHERE products_id='" . $rp_id . "'";
$result1 = mysql_query($res);
$row1 = mysql_fetch_array($result1);
echo '<li>'.$row1['products_name'].'</li>';
}
echo '</ul>';
However, it displays nothing.. Is there something wrong with my code? Do you have any solution for this?
Thank you.

Answer 1

You have placed the actual database query section outside of the loop.
You should include this within the foreach loop, so that every time, a new query runs and you will receive the results as you anticipated.
foreach($lst_rp as $rp_id) {
$res = "SELECT products_id, products_name FROM ".TABLE_PRODUCTS_DESCRIPTION." WHERE products_id='" . $rp_id . "'";
$result1 = mysql_query($res);
while($row1 = mysql_fetch_array($result1)) {
echo $row1['products_name'];
}
}
And one more thing, since you are using double quotes to wrap your query, you can shorten it two
$res = "SELECT products_id, products_name FROM ".TABLE_PRODUCTS_DESCRIPTION." WHERE products_id='$rp_id'";
Update
Use the following code to ensure the <li> is not empty
foreach($lst_rp as $rp_id) {
$res = "SELECT products_id, products_name FROM ".TABLE_PRODUCTS_DESCRIPTION." WHERE products_id='" . $rp_id . "'";
$result1 = mysql_query($res);
$row1 = mysql_fetch_array($result1);
echo !empty($row1['products_name']) ? '<li>'.$row1['products_name'].'</li>' : '';
}

Answer 2

Please try with this
$sql = "SELECT related_products_ids FROM ".TABLE_RELATED_PRODUCTS." where products_id = '" . (int)$_GET["products_id"]."'";
$result = mysql_query($sql);
$row = mysql_fetch_array($result);
$lst_rp = explode(',', $row['related_products_ids']);
foreach($lst_rp as $rp_id) {
$res = "SELECT products_id, products_name FROM ".TABLE_PRODUCTS_DESCRIPTION." WHERE products_id='" . $rp_id . "'";
$result1 = mysql_query($res);
$row1 = mysql_fetch_array($result1);
echo $row1['products_name'];
}

Answer 3

In your code
$lst_rp = explode(',', $row['related_products_ids']);
gives you an array of related product ids which is fine. But then in your loop:
foreach($lst_rp as $rp_id) {
$res = "SELECT products_id, products_name FROM ".TABLE_PRODUCTS_DESCRIPTION." WHERE products_id='" . $rp_id . "'";
}
you are overwriting the value of $res in each loop iteration so when you do the next query
$result1 = mysql_query($res);
it will only fetch the last related product id from the database.

Answer 4

please change only
$row1=mysql_fetch_assoc($result1);
i means
foreach($lst_rp as $rp_id) {
$res = "SELECT products_id, products_name FROM ".TABLE_PRODUCTS_DESCRIPTION." WHERE products_id='" . $rp_id . "'";
$result1 = mysql_query($res);
$row1 = mysql_fetch_assoc($result1);
echo $row1['products_name'];
}