PDO binds n times same value with foreach - php

Question

I have function in PHP, which should bind in MySQL IN statement so many variables, that is in array.
My problem is that variable and key is changing but function bind only last value n times.
I don't have idea where is the problem...
Here is my class method:
public function getOtListByOtNumbers($conditions){
$data_array = $conditions[SEARCH_OT];
# To find last key (remove coma)
$quantity = count($data_array);
$marks = '';
# Bind name string && rewriting value as integer
foreach ($data_array as $key => $value){
$i = $key+1;
if ($i == $quantity){
$marks .= ':key'.$i;
}
else {
$marks .= ':key'.$i.', ';
}
}
# Query
$sql="
SELECT
c_int_id,
c_ot,
c_tickets_amount,
c_basket_value,
c_person,
c_company,
c_city,
c_package_number,
c_delivery_method,
c_ot_date,
c_email,
c_phone,
c_comment,
c_send
FROM ws_orders
WHERE c_ot IN (".$marks.")
ORDER BY c_int_id DESC
LIMIT :first, :last ";
$stmt = $this->PDO->prepare($sql);
# Bind n values
// Here is a problem
var_dump($data_array); // var dump 1
foreach ($data_array as $key => $param){
$key_number = $key +1;
$key_name = 'key'.$key_number;
$stmt->bindParam($key_name, $param, PDO::PARAM_INT);
var_dump($key_name); // var dump 2
var_dump($param); // var dump 3
}
# Bind limit values
$stmt->bindParam('first', $conditions[OT_SEARCH_FIRST_ROW], PDO::PARAM_INT);
$stmt->bindParam('last', $conditions[OT_SEARCH_ROW_LIMIT], PDO::PARAM_INT);
# If executed return result
if ($stmt->execute() != FALSE) {
$stmt_result = $stmt->fetchAll();
$stmt->closeCursor();
var_dump($stmt_result); // var dump 4
# If not executed print debug and return FALSE
} else {
var_dump($stmt->errorInfo());
$this->debugQuery($stmt);
$stmt_result = FALSE;
}
return $stmt_result;
}
Here are var dupms:
var dump 1
array (size=2)
0 => string '2761531'
1 => string '2760650'
var dump 2 & 3
string 'key1' (length=4)
string '2761531'
string 'key2' (length=4)
string '2760650'
SQL query from this execution
SELECT
c_int_id,
c_ot,
c_tickets_amount,
c_basket_value,
c_person,
c_company,
c_city,
c_package_number,
c_delivery_method,
c_ot_date,
c_email,
c_phone,
c_comment,
c_send
FROM ws_orders
WHERE c_ot IN ('2760650', '2760650')
ORDER BY c_int_id DESC
LIMIT 0, 30
So what I am doing wrong?
EDIT
So i did it ;)
The problem was with foreach
Instead of:
foreach ($data_array as $key => $param){
$key_number = $key +1;
$key_name = 'key'.$key_number;
$stmt->bindParam($key_name, $param, PDO::PARAM_INT);
var_dump($key_name); // var dump 2
var_dump($param); // var dump 3
}
I give:
for ($key_number = 0; $key_number < $quantity + 1; $key_number++) {
$key_name = 'key'.$key_number;
$stmt->bindParam($key_name, $data_array[$key_number], PDO::PARAM_INT);
}
And it works, but i still don't know what the problem was with earlier foreach...

Answer 1

There is the difference between PDO::bindParam() and PDO::bindValue(). PDO::bindParam binds reference, not value. When foreach process ends, $param will reference to the last array value. In the time of execute call all binded references will be evaluated to same value.
Official PDO::bindParam documentation says:
Unlike PDOStatement::bindValue(), the variable is bound as a reference
and will only be evaluated at the time that PDOStatement::execute() is
called.
If you want bind values in foreach use PDO::bindValue.

Answer 2

If you pass the variable as reference it would work fine for value, but won't work for key.
Example:
foreach ($data_array as $key => &$param) {
$key_number = $key + 1; //this won't work
$key_name = 'key' . $key_number;
$stmt->bindParam($key_name, $param, PDO::PARAM_INT);
var_dump($key_name); // var dump 2
var_dump($param); // var dump 3
}

Answer 3

The problem is that BindParam Passes the second value by reference. PHP reuses (or appears to in this case) the address of the $param, and not the actual value.
Your foreach could have used:
$stmt->bindParam($key, $data_array[$key]);
This has the effect of binding the address location of the array at that key location, so when your sql executes, it gets the right value.
You probably wanted:
$stmt->bindValue($key, $param);
which should evaluate in the foreach loop instead of at the execute statement, and is a passed value instead of an address location.