警报框后如何取回所有数据？

Question

我有25个字段的表格。当出现错误并显示警告框时。在警报框上单击“确定”后，所有字段均变为空白。如何防止表格成为空白。到目前为止，我已经尝试过了。

$job_confrm = $_POST['job_confrm'];
$training_no = $_POST['training_no'];
$created_on = date('Y-m-d H:i:s');
$unique_id = rand(100000, 999999);

$ftquery = mysqli_query($con, "SELECT * From hr_employee_service_register where employee_id='$employee_id' AND status='1'");

if (mysqli_num_rows($ftquery) > 0) {
    echo '<script>alert("Employee Already Registered");
    preventDefault();
    return false;</script>';
}