PHP/SQL – SQLSTATE[23000]: Integrity constraint violation

Warning: Array to string conversion in C:\Users\Caleb\PhpstormProjects\barberspoint-flakkee\appointment.php on line 75

SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`barbershop`.`appointments`, CONSTRAINT `FK_client_appointment` FOREIGN KEY (`client_id`) REFERENCES `clients` (`client_id`) ON DELETE CASCADE)

The PHP code: (I have put text which line 75 is)

$stmt_appointment->execute(array(Date("d-m-Y H:i"), $client_id, $selected_employee, $start_time, $end_time));

if (isset($_POST['submit_book_appointment_form']) && $_SERVER['REQUEST_METHOD'] === 'POST') {
            // Selected SERVICES

            $selected_services = $_POST['selected_services'];

            // Selected EMPLOYEE

            $selected_employee = $_POST['selected_employee'];

            // Selected DATE+TIME

            $selected_date_time = explode(' ', $_POST['desired_date_time']);

            $date_selected = $selected_date_time[0];
            $start_time = $date_selected . " " . $selected_date_time[1];
            $end_time = $date_selected . " " . $selected_date_time[2];


            //Client Details

            $client_first_name = test_input($_POST['client_first_name']);
            $client_last_name = test_input($_POST['client_last_name']);
            $client_phone_number = test_input($_POST['client_phone_number']);
            $client_email = test_input($_POST['client_email']);

            $con->beginTransaction();

            try {
                // Check If the client's email already exist in our database
                $stmtCheckClient = $con->prepare("SELECT * FROM clients WHERE client_email = ?");
                $stmtCheckClient->execute(array($client_email));
                $client_result = $stmtCheckClient->fetch();
                $client_count = $stmtCheckClient->rowCount();

                if ($client_count > 0) {
                    $client_id = $client_result["client_id"];
                } else {
                    $stmtgetCurrentClientID = $con->prepare("SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'barbershop' AND TABLE_NAME = 'clients'");

                    $stmtgetCurrentClientID->execute();
                    $client_id = $stmtgetCurrentClientID->fetch();

                    $stmtClient = $con->prepare("insert into clients(first_name,last_name,phone_number,client_email) 
                                    values(?,?,?,?)");
                    $stmtClient->execute(array($client_first_name, $client_last_name, $client_phone_number, $client_email));
                }


                $stmtgetCurrentAppointmentID = $con->prepare("SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'barbershop' AND TABLE_NAME = 'appointments'");

                $stmtgetCurrentAppointmentID->execute();
                $appointment_id = $stmtgetCurrentAppointmentID->fetch();

                $stmt_appointment = $con->prepare("insert into appointments(date_created, client_id, employee_id, start_time, end_time_expected ) values(?, ?, ?, ?, ?)");
                **THIS IS LINE 75** $stmt_appointment->execute(array(Date("d-m-Y H:i"), $client_id, $selected_employee, $start_time, $end_time));

                foreach ($selected_services as $service) {
                    $stmt = $con->prepare("insert into services_booked(appointment_id, service_id) values(?, ?)");
                    $stmt->execute(array($appointment_id[0], $service));
                }

                echo "<div class = 'alert alert-success'>";
                echo "Great! Your appointment has been created successfully.";
                echo "</div>";

                $con->commit();
            } catch (Exception $e) {
                $con->rollBack();
                echo "<div class = 'alert alert-danger'>";
                echo $e->getMessage();
                echo "</div>";
            }
        }

I just don’t understand how this happen. #Hobby

>Solution :

with your code

$stmtgetCurrentClientID = $con->prepare("SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'barbershop' AND TABLE_NAME = 'clients'");
$stmtgetCurrentClientID->execute();
$client_id = $stmtgetCurrentClientID->fetch();

the variable $client_id is an array. then you try to enter the whole array as id. the next line shows how it should be right.

$stmt_appointment->execute(array(Date("d-m-Y H:i"), $client_id, ... // your code
$stmt_appointment->execute(array(Date("d-m-Y H:i"), $client_id['AUTO_INCREMENT'], ...

and by the way: $con->lastInsertId(); is a better way to get the current id after an insert instead of select AI before an insert.