Results UNDEFINED in SQL query and php - php

Question

I am new when it comes to php, SQL and still learning, I am trying to get the last 4 string value of my column where the value is a telephone numbers: (7258787)
I am trying to display the last 4 string even the search query is full 7 string (8787) base on what i have read SUBSTRING(column_name, -4) will result the last 4 strings from the right.
my codes returns undefined, can you enlighten me with this?
if (isset($_GET['telephone'])) {
$data = "%".$_GET['telephone']."%";
$sql = 'SELECT telephone, SUBSTRING(telephone,-4)FROM employee';
Using this:
$sql = 'SELECT * FROM employee WHERE telephone like ?';
will result the correct value of 7258787 but it will result the whole string(telephone numbers) that i type on a search box
Thank you in advance
This is the whole code:
This is not the answer but the whole script, (credits to Israel Barragan)
In my database I have employee as table and the columns are 'ID', 'NAME', 'TELEPHONE', and 'EMAIL'
<?php
header('Content-Type: application/json');
require_once 'Connectiondb.php';
$conn = dbConnect();
$OK = true; // We use this to verify the status of the update.
if (isset($_GET['telephone'])) {
// Create the query
$data = "%".$_GET['telephone']."%";
$sql = 'SELECT * FROM employee WHERE telephone like ?';
// we have to tell the PDO that we are going to send values to the query
$stmt = $conn->prepare($sql);
// Now we execute the query passing an array toe execute();
$results = $stmt->execute(array($data));
// Extract the values from $result
$rows = $stmt->fetchAll();
$error = $stmt->errorInfo();
//echo $error[2];
}
// If there are no records.
if(empty($rows)) {
echo json_encode( array('error'=>'There were not records','0'=> 'There were not records'));
}
else {
echo json_encode($rows);
}
?>
sorry I am new to stackoverflow,

Answer 1

You can bind the result in your query, and then get the last 4 digits from that to display.
For instance, you can do this
(not you aren't binding your parameters. You need to do something like this)
$stmt->bind_param("s", $data);
and then execute it like this:
$stmt->execute();
In your query instead of using select *, name the specific keys and then you can bind the result like this (assuming all you need is the phone number:
$stmt->bind_result($telephone);
then get the result like so:
$stmt->fetch();
then you can just get a substring off of $telephone like so (in php it is substr())
echo substr($telephone,-4);
(oh yeah and don't forget to close your object with
$stmt->close();
after you are done)
Edit:
Here's your query put together to get the substring
$data = "%".$_GET['telephone']."%";
$stmt = $conn->prepare("SELECT telephone FROM employee WHERE telephone like ?");
$stmt->bind_param("s", $data);
$stmt->execute();
$stmt->bind_result($telephone);
$stmt->fetch();
echo substr($telephone,-4);
$stmt->close();