How to debug inside a while loop

[justin7410]

Hey guys,

 

I am trying to grab and loop data from my DB with a while loop and extract() function.

 

right now i have something like this:

 

echo '<div>'; // CONTAINER DIV
echo '<h2>News about '. $db_name. '</h2>';

$query = 'SELECT * FROM `news_to_people` WHERE `people_db_id` = '.$db_id;
$r_query = mysql_query($query);

while($rows=mysql_fetch_assoc($r_query)){
extract($rows);

$new_q = 'SELECT * FROM `news` WHERE `id` = '.$news_id;
$run_q = mysql_query($new_q);

$rows = mysql_fetch_assoc($run_q);
extract($rows);
echo '<ul>';
echo '<l1><a href="article?articleid='.$id.'&name='.$db_name.'">'.$title.'<br></l1>';
echo '</ul>';
}
echo '</div>'; // END TO CONTAINER

Now here i get the loop to fire correctly and execute.

 

It then loops all 170+ links except in the middle of the loop , there is an error:

 

 

Warning: extract() expects parameter 1 to be array, boolean given in/home/justin/public_html/include/demo/center_content.php on line 351

 

 

so this means that i have a failed 2nd query somewhere in that it is skipping inside the while loop.

 

i need to debug and find which query is bringing this error.

 

my question is what is the best way i can write an if statement to see which query is failing or which query is not returning a proper array. also my if the query was failing wouldn't the error be asking for a proper resource ? this means the query is firing correctly and the extract() function is failing to receive all the rows. meaning that one of the rows must be returning empty or zero ? 

 

any help is much appreciated.

[Skewled]

Add or die() to the 2nd query and see what MySQL states.

[Barand]

Several points worth mentioning with that script.

 

1. You only want the news_id in that first query so "SELECT news_id FROM ....". Don't use "SELECT * ", select only what you need .
2. A query returning no rows is not an error.
3. Don't run queries inside loops - use a JOIN to retrieve the data with a single query.
4. mysql_ library has been replaced by mysqli_ and will not be available after v5.4

$query = "SELECT n.id
    , n.title
    FROM news_to_people np
        INNER JOIN news n ON np.news_id = n.id
    WHERE np.people_db_id = $db_id";

$res = $db->query($query);
echo "<div>";
while (list($id, $title) = $res->fetch_assoc()) {
  echo '<ul>';
  echo '<l1><a href="article?articleid='.$id.'&name='.$db_name.'">'.$title.'<br></l1>';
  echo '</ul>';
}
echo '</div>'; // END TO CONTAINER

[Barand]

Amendment to above ^^

 

Change fetch_assoc() to fetch_row()