connect two sites via php step 1

i have a php 5.6 casino script mysql
i have a php 7 pokersite this job consist of
on pokersite edit registration page to check for users in casino then if name if free to submit reg form to database in the casino too
username firstname lastname email and password only , couple of extra feild may need to be added
password will need to be md5 to work as casino pasword is md5, poker site is not
simply new connection .php
$con = @mysqli_connect('localhost', 'username', 'password', 'database','port');
then submit new form to my subdmoain casino sites database md5 the password first tho
then edit forgot password button on pokersite to change passwords in both databases
thanks first step

Requirements

i have a php 5.6 casino script mysql
i have a php 7 pokersite this job consist of
on pokersite edit registration page to check for users in casino then if
name if free to submit reg form to database in the casino too
username firstname lastname email and password only , couple of extra feild may need to be added
password will need to be md5 to work as casino pasword is md5, poker site is not
simply new connection .php
$con = @mysqli_connect('localhost', 'username', 'password', 'database','port');
then submit new form to my subdmoain casino sites database md5 the password first tho
then edit forgot password button on pokersite to change passwords in both databases
thanks first step

Skills Required

Php Database Mysql Mysqli Sql