Inserting array values into SQL - php

Question

I randomized a set of questions using the following code:
for($i=0; $i < count($nwi); $i++)
$itemorder[$i] = $i;
shuffle($itemorder);
$_SESSION["itemorder"] = $itemorder;
A few pages later, a portion of the questions are presented:
for ($i=0; $i<40; $i++) {
if ($i % 10 ==0) echo $header;
echo '<tr class="';
if(in_array($itemlabel[$_SESSION["itemorder"][$i]], $errors)) echo 'skip';
elseif ($i % 2 == 0) echo 'even';
else echo 'odd';
echo '">';
echo '<td>' . ($i + 1) . ".</td><td>" . $itemtext[$_SESSION["itemorder"][$i]] . '</td>';
for ($j = 1; $j <= 6; $j++) {
echo "\n" . '<td';
if ($j == 6) echo ' style="background-color:#999;"';
echo '><input type="radio" name="';
echo $itemlabel[$_SESSION["itemorder"][$i]];
echo '" value="';
echo $j; //value of the input
echo '"';
if ($_POST[$itemlabel[$_SESSION["itemorder"][$i]]] == $j) echo " checked";
echo '></td>';
}
At the end of the survey, I am trying to put the answers to the questions (which should range in value from 1-8) into my SQL database:
"INSERT INTO surveydata
(id, agree_pppg_01,agree_pppg_02,agree_pppg_03,....
VALUES
('$_SESSION[id]', '$_SESSION[itemorder][0]',
'$_SESSION[itemorder][1]', '$_SESSION[itemorder][2]',
'$_SESSION[itemorder][3]',...
I am getting only zeros in my SQL database regardless of how I answer the questions. Any suggestions?

Answer 1

Well, first I don't see anything assigning anything to the session values, but the issue with your code is in this pattern: '$_SESSION[itemorder][1]'. First, I would make sure that MySQL is expecting a varchar there and not an int. If it is an int, good form would be to make sure it isn't quoted.
More importantly, though, when you have an associative array in PHP, you need to make sure PHP expects that.
This
$a = array("hi"=>array("world"=>0)); echo "$a[hi][world]";
Outputs
Array[world]
Put braces around the lookup to make sure it knows to treat it as an array, and then put quotes around all string indexes:
// note the braces and quotes
$a = array("hi"=>array("world"=>"here")); echo "{$a["hi"]["world"]}";
Outputs
"here"
But, I wonder if you wouldn't be better off just using implode:
$columns = implode(',', $_SESSION['itemorder']);
$query = "INSERT INTO surveydata
(id, agree_pppg_01,agree_pppg_02,agree_pppg_03,....
VALUES ('{$_SESSION["id"]}', $columns )";
I do feel obliged to point out that that system does not seem scaleable, and column names like agree_pppg_02 are not descriptive. You may want to go to the codereview stackexchange site to see if they can't offer tips on database design.