Issue with bulk insert in mysql using pdo and php - php

Question

I am trying to insert bulk records in mysql using pdo but for some reason I am not able to build up the query.
My POST looks like this
Array
(
[ques_1] => dsadasd
[ques_2] => 5
[ques_3] => dasdsad
[ques_4] => 23/7/2014
[savecontinue] => Save & Continue
)
My desired array should look like this
Array
(
[quid] => 1
[answer] => dasdsad
)
Array
(
[quid] => 2
[answer] => on
)
Array
(
[quid] => 3
[answer] => dasdsad
)
Array
(
[quid] => 4
[answer] => 23/7/2014
)
My code looks like this
foreach($_POST as $k=>$v)
{
if($k != 'savecontinue' and $k != 'skipsave')
{
list(,$qid) = explode("_",$k);
$insertData[$qid] = $v;
}
}
$sql = "INSERT INTO answers (quid, answer)
VALUES (:quid, :answer)";
$query = $this->db->prepare($sql);
$query->execute($insertData);
The error is PDOStatement::execute(): SQLSTATE[HY093]: Invalid parameter number: number of bound variables does not match number of tokens
Note: I have simplified/reduced the query params and code for better understanding.

Answer 1

Well it seems to me that you would be better of with something like this.
You also were passing to many parameters to the INSERT, the array you pass must have only those values required by the query and be named with the ':' in front.
// prepare the query for multiple use later
$sql = "INSERT INTO answers (userid, catid, quid, qstep, answer)
VALUES (:userid, :catid, :quid, :qstep, :answer)";
$query = $this->db->prepare($sql);
// create an array of inputs
for ($x=1; $x < 5; $x++ ) {
$insertData[] = array( ':userid' => 1,
':catid' => $_POST['catid'],
':quid' => $x,
':qstep' => 1,
':answer' => $_POST['ques_'.$x]);
}
// loop over the array of inputs
foreach ( $insertData as $data ) {
$query->execute($data);
}

Answer 2

Change the following:
$insertData = array("$qid"=>"$v");
to:
$insertData[$qid] = $v;