erd is graphical tool for modeling data.

table user interconnected with shedule and reminder. user with shedule that one tomany, and a reminder with one to many users. in the table the user we have a roleattribute, id_username, id_number, name, and in the user table there are servants in the primary key of that his id_username.
table user had one to many relationship to the reminder in reminder, there is attribute hour, content, and date.
table user had one to one to schedule student there is attribute tmes, matkul, hari , id_student  and lecture schedule there is attribute day, times, courses,location, class, id_Lecturer.