Parse error: syntax error, unexpected '@' in /home/....../..../

Question

I've these tables users,tasks,roles,permissions & a pivot table permissions_roles.

roles:

1. role_id: auto_increament
2. role_name: admin/standard

permissions:

1. permission_id: auto_increament
2. permission_name: create/edit/delete

Pivot table: permissions_roles

1. p_id(FOREIGN KEY (r_id) REFERENCES roles(role_id))
2. r_id(FOREIGN KEY (p_id) REFERENCES permissions(permission_id))

But when I'm trying to insert values into the pivot table, by writing this code:

function roles($role_name){
        mysqli_query($this->connect,"INSERT INTO roles ( role_name ) VALUES ('$role_name')");
        SET @r_id = LAST_INSERT_ID();
    }

Then I'm getting this error:

Parse error:

syntax error, unexpected '@' in /home/directory/project_folder/users.php

I need to assign multiple permissions for each roles. Please help.