== User Login

==== Actors: **Registered User (USER / ADMIN / INSTRUCTOR)**

**1.** Check if User Exists.”.

The system checks whether a user with the given email exists in the database.

{{{#!sql
SELECT id, password, role
FROM user_entity
WHERE email = :email;



}}}

**2.** Password Validation (Application Logic).

The entered password is compared with the stored hashed password.

If the password is invalid, the login process is stopped.

If the password is valid, the process continues.


**3.** Load User Type Based on Role.

After successful authentication, the system loads the user type according to the role.

**#** If the role is USER:
{{{#!sql
SELECT id
FROM users
WHERE id = :userId;



}}}

**#** If the role is ADMIN:
{{{#!sql
SELECT id
FROM administrators
WHERE id = :userId;




}}}

**#** If the role is INSTRUCTOR:
{{{#!sql
SELECT id
FROM instructors
WHERE id = :userId;



}}}