Limitations of the File-Based Approach

• Separation and Isolation of Data
• Duplication of Data

ANSI-SPARC Three-Level Architecture

1. External Level - users
2. Conceptual Level - describing what data is stored in the database and relationships among the data.
3. Internal Level - describes how the data is stored in the database.
4. Database - physical data organization

Catalog

• A set of schemas that constitute the description of a database

Schema

• The structure basically ( tables and shit )

DDL ( Data Definition Language )

• commands that define a database, including creating, altering and dropping tables and establishing constraints

DML ( Data Manipulation Language )

• provides data manipulation operations on data in the database.

Procedural DML