1. Physical – (how data)
2. logical – (what data)
3. view level – (view data)
1. Physical Level is the lowest level. It describes how the data is actually stored in the storage medium. At physical level complex low-level data structures are described in detail.
2. Logical level describes what data are stored in the database and what relationships exist among data. Here database is described in terms of simple structure. Records are defined in this level. Programmers work at this level.
3. View level is the highest level of data abstraction. It is concerned with the way in which the users view the database. It describes only part of the database.
