PHP PDO MySQL query prints blank

Question

Going through a PHP MySQL tutorial and switching the PHP out for PDO; at any rate, my query is coming up blank.

$get_cat = $that->dbh->query("SELECT `cat_name`, `cat_desc` FROM `categories`");

            if(isset($get_cat))
            {
        while($row = $get_cat->fetch(PDO::FETCH_ASSOC))
            {
                printf("
                <tr>
                    <td>".$row['cat_name']." : ".$row['cat_desc']."</td>
                </tr>
                ");
            }
            }
            else
                {
                    echo '<tr><td>return is false</td></tr>';
                }

$That refers to:

include('db.php');
$that = new lib();

OLD: So, why is my query blank? Before putting the die in it would return Boolean and give in an error in the loop with the die in it just comes up blank. The categories table has data in it and the page is refreshed on submission for new entries. NEW: Fatal error: Call to a member function fetch() on a non-object in C:\wamp\www\forum\create_category.php on line 36

Line 36 is the while loop line.

jeroen · Accepted Answer · 2013-02-12 14:29:00Z

3

mysql_fetch_array is not PDO. You would need something like:

while($row = $get_cat->fetch(PDO::FETCH_ASSOC))

To get your rows.

Nor can you use mysql_error() to get the error. You could use for example $that->dbh->errorInfo() but you should look into exceptions for a more robust way to catch all errors.

Edit: You should check what the error is. Using isset is pointless as you have just assigned a value to it, so it will always be set.

edited Feb 12, 2013 at 14:29

answered Feb 12, 2013 at 13:59

jeroen

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6 Comments

Louis Milotte Over a year ago

jeroen and @sgeddes thanks! I made changes to the query and switched from the PHP while to the PDO while. The error now received is Fatal error: Call to a member function fetch() on a non-object in C:\wamp\www\forum\create_category.php on line 36. line 36 is the while loop. Updating post with new code to include error.

jeroen Over a year ago

@Louis Milotte Check what the error is using errorInfo(). And post your connection script, perhaps there are remains of mysql_* functions as well.

Louis Milotte Over a year ago

I tried using errorInfo() as print_r($that->dbh->errorInfo()); but i'm getting not getting anything from it. Connection script is

function con($host,$db,$user,$pass) 				{ 					$this->dbh = new PDO("mysql:host=$host;dbname=$db","$user","$pass"); 				}

jeroen Over a year ago

@Louis Milotte Without seeing your include it is impossible to tell what is wrong.

Louis Milotte Over a year ago

include is include('db.php'); db.php houses the class containing the connection function; however, the query for categories is on the same page as the insert to categories; the insert works.. the select does not.

|

Your Common Sense · Accepted Answer · 2013-02-12 15:23:39Z

1

You need to tell PDO to throw errors.

$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$res = $that->dbh->query("SELECT cat_name, cat_desc FROM categories");
while($row = $res->fetch())
{
    echo "<tr><td>$row[cat_name] : $row[cat_desc]</td></tr>\n";
}

run your code, read the error message and take appropriate action

Don't forget to add the first line into your db.php file, to make the setting permanent

edited Feb 12, 2013 at 15:23

answered Feb 12, 2013 at 14:41

Your Common Sense

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2 Comments

Louis Milotte Over a year ago

This printed the error and it was resolved; as simple as I forgot I didn't use cat_desc on this table but cat_description. @jeroen This was the solution. Thanks to everyone.

Louis Milotte Over a year ago

@jeroen I responded to your post giving the PDO connection; it was function con($host,$db,$user,$pass) { $this->dbh = new PDO("mysql:host=$host;dbname=$db","$user","$pass"); } it was given 17-18min ago from time of this post.

sgeddes · Accepted Answer · 2013-02-12 13:59:54Z

1

Your query is incorrect -- is this what you're trying to do?

SELECT `categories`.`cat_name`, `categories`.`cat_desc` FROM `categories`

Hard to know without seeing you table structure.

answered Feb 12, 2013 at 13:59

sgeddes

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