不显示来自mysql的数据

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

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 2

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 3

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 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'];

}