PHP Form data into database - php

Question

I've created a form that inserts data into a database.
I've been given the two functions to get the data and display it, these are located in a file called queryDb.php:
function addCustomer($fname, $lname, $address, $phone) {
$db = new MyDB();
if(!$db){
echo '<script type="text/javascript">alert("'.$db->lastErrorMsg().'");</script>';
} else {
//echo "Opened database successfully\n";
}
$sql ='INSERT INTO CUSTOMERS (FIRSTNAME, LASTNAME, ADDRESS, PHONE) VALUES ("'.$fname.'", "'.$lname.'", "'.$address.'", "'.$phone.'");';
$db->query($sql);
}
get function:
function getCustomers($searchTerm = null) {
$db = new MyDB();
if(!$db){
echo '<script type="text/javascript">alert("'.$db->lastErrorMsg().'");</script>';
} else {
//echo "Opened database successfully\n";
}
if(!$searchTerm) {
$sql ='SELECT * from CUSTOMERS;';
} else {
$sql ='SELECT * FROM CUSTOMERS WHERE FIRSTNAME LIKE "'.$searchTerm.'" OR LASTNAME LIKE "'.$searchTerm.'" OR ADDRESS LIKE "'.$searchTerm.'" OR PHONE LIKE "'.$searchTerm.'"';
}
$ret = $db->query($sql);
$array = [];
if(!$ret){
echo $db->lastErrorMsg();
return [];
} else {
while($row = $ret->fetchArray(SQLITE3_ASSOC) ){
$array[] = $row;
}
$db->close();
return $array;
}
}
In my reviewsubmit.php I have this up the top:
<?php
require_once "queryDb.php";
$firstname = $_POST["firstname"];
$lastname = $_POST["lastname"];
$address = $_POST["address"];
$phone = $_POST["phone"];
addCustomer($firstname, $lastname, $address, $phone);
?>
And this is my form:
<form action="reviewsubmit.php" method="post">
<label for="firstname">First name:</label>
<input type="text" id="firstname" name="firstname" placeholder="Enter First name" required /><br>
<label for="lastname">Last Name:</label>
<input type="text" id="lastname" name="lastname" placeholder="Enter Last name" required /><br>
<label for="address">Address:</label>
<input type="text" id="address" name="address" placeholder="Enter Address" required /><br>
<label for="phone">Phone:</label>
<input type="text" id="phone" name="phone" placeholder="Enter Phone" required /><br>
<input type="submit" name="Submit" value="Submit" />
</form>
The problem is the first time when I click 'Submit', it puts empty values into the Database, when I click 'Submit' a second time it puts the actual values I typed in:
image
What is causing it to add empty values into the database?

Answer 1

Try with this
<?php
require_once "queryDb.php";
if(isset($_post['Submit')){
$firstname = $_POST["firstname"];
$lastname = $_POST["lastname"];
$address = $_POST["address"];
$phone = $_POST["phone"];
addCustomer($firstname, $lastname, $address, $phone);
}
?>

Answer 2

Checking that the submitted values are not empty or null before inserting them into the Database is your best bet.
<?php
require_once "queryDb.php";
$firstname = isset($_POST["firstname"])? htmlspecialchars(trim($_POST["firstname"])) : null;
$lastname = isset($_POST["lastname"]) ? htmlspecialchars(trim($_POST["lastname"])) : null;
$address = isset($_POST["address"]) ? htmlspecialchars(trim($_POST["address"])) : null;
$phone = isset($_POST["phone"]) ? htmlspecialchars(trim($_POST["phone"])) : null;
// CHECK THAT YOU DON'T HAVE NULL OR EMPTY FIELD VALUES BEFORE INSERTING ANYTHING INTO DATABASE
if(!is_null($firstname) && !is_null($lastname) && !is_null($address) && !is_null($phone) ){
addCustomer($firstname, $lastname, $address, $phone);
}
?>

Answer 3

A row is inserted into the database the first time you load the page. This is happening because you are not checking if the form has actually been submitted.
You will need to check if the form is already posted. You can do that like this:
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
IF (isset($_POST['submit'])) {
// Do the database stuff
}
}
// Your form here

Answer 4

You can check if $_POST['Submit'] is set and $_POST is not empty before calling addCustomer function. PHP function empty and isset may help you with this.