Initially, there was a project written in Asp.NET with the Oracle database, to which they decided to add another application. The second application was purchased. It is written in PHP, uses the MySQL database.
Now you need to combine the sites so that when you click a button on one site, you move to the second, without having to enter a password and login, authorization occurs automatically, and also to implement an algorithm that, when registering on one site, automatically adds this user to the second site.
Here are the options that have ripened in my inexperienced june brain:
1) Rewrite one of the applications for another database, but here there is a problem with not knowing PHP, and changing the database in the main project is also quite problematic.
2) Creating a trigger in the Oracle or MySQL database itself, so that when Insert'e, Email and Hash are sent by a SQL query directly to another database. But I’m not sure if it is safe, or if it can be implemented at all.
3) Connecting two databases with each of the projects, but as far as I understand, the variant is very curved. Yes, and PHP problems with the knowledge of PHP will let you know about yourself.
4) The database stores username and password from the user. The login is in a normal form, and the password is encrypted. I thought about somehow transmitting this particular Hash from the database, so that the second site would normally accept it and authorize me. But there is a problem with the fact that even with the same password this Hash is different.
I would like to hear your option for implementing a solution to this problem, or the answer to which of my options is the safest, easiest and fastest. implementation.