Answers for "linux update php"

update php version ubuntu 7.3

sudo apt-get install software-properties-common
sudo add-apt-repository ppa:ondrej/php
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install -y php7.3

ubuntu upgrade php to 7.3

sudo apt-get install software-properties-common
sudo add-apt-repository ppa:ondrej/php
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install -y php7.3

update php

//SQL query for updating php post from a form using sql
$firstName = $_POST['firstName'];
mysqli_query($con,"UPDATE member SET  firstName='$firstName' WHERE id=1");

or 
// actually updating php version
go contact hosting provider, or login to cpanl look for 'php' settings or 'MultiPHP Manager'