Update query from PHP does not work - php

Question

I run this update query from PHP code:
$update_begin_insurance = "UPDATE `vehicles`
SET `begin_insurance_date` = '$begin_insurance'
WHERE `plate` = '$plate'";
$conn->query($update_begin_insurance);
$conn is a PDO object.
The problem is that any exception is thrown by $conn, but the vehicles table in my database is not updated. So, I've tried to run this query directly through phpmyadmin, and it works correctly, so I think it's a PHP problem, but I can't figure out where the problem is.
My begin_insurance_date column is of type DATE, and $begin_insurance is a string in the correct format (YYYY-MM-DD, I've tried this code with 2017-06-10).
I'm using MySQL DBMS
This is the echo of $update_begin_insurance:
UPDATE `vehicles`
SET `begin_insurance_date` = '2017-06-10'
WHERE `plate` = 'ccccc'
UPDATE
This is the full PHP code of my page:
<?php
require_once "connect_db.php";
$plate = $_POST["plate"];
$begin_insurance = $_POST["begin_insurance"];
$end_insurance = $_POST["end_insurance"];
$fuel_economy = $_POST["fuel_economy"];
$fuel_type = $_POST["fuel_type"];
$response = array();
try
{
$conn->beginTransaction();
if ($begin_insurance != "")
{
$update_begin_insurance = "UPDATE `vehicles`
SET `begin_insurance_date` = '$begin_insurance'
WHERE `plate` = '$plate'";
$conn->query($update_begin_insurance);
}
if ($end_insurance != "")
{
$update_end_insurance = "UPDATE `vehicles`
SET `end_insurance_date` = '$end_insurance'
WHERE `plate` = '$plate'";
$conn->query($update_end_insurance);
}
if ($fuel_economy != "")
{
$update_fuel_economy = "UPDATE `vehicles`
SET `fuel_economy` = $fuel_economy
WHERE `plate` = '$plate'";
$conn->query($update_fuel_economy);
}
if ($fuel_type != "")
{
$update_fuel_type = "UPDATE `vehicles`
SET `id_fuel` = $fuel_type
WHERE `plate` = '$plate'";
$conn->query($update_fuel_type);
}
$response["post"] = $_POST;
$response["error_code"] = "0";
$response["error_message"] = "none";
$response["driver_error_code"] = "0";
}
catch (PDOException $e)
{
if ($conn->inTransaction())
{
$conn->rollBack();
}
$response["post"] = $_POST;
$response["error_code"] = $e->getCode();
$response["error_message"] = $e->getMessage();
$response["driver_error_code"] = $e->errorInfo[1];
}
echo json_encode($response);
?>
As I said before, I don't get any exception (as you can see, I also print the $_POST array to check if the params are received correctly, and yes, they are).
This is what echo json_encode($response) prints:
{
"post":
{
"plate":"ccccc",
"begin_insurance":"2017-06-10"
},
"error_code":"0",
"error_message":"none",
"driver_error_code":"0"
}
I'm sure the connection works correctly because I've got others PHP files which execute some INSERT queries, and they works correctly.

Answer 1

I've solved the problem, I was missing the $conn->commit().