Database schema
The schema (pronounced skee-ma) of a database system is its structure described in a formal language supported by the database management system (DBMS). In a relational database, the schema defines the tables, the fields in each table, and the relationships between fields and tables.
Schemas are generally stored in a data dictionary. Although a schema is defined in text database language, the term is often used to refer to a graphical depiction of the database structure.[1]
Levels of database schema
- Conceptual schema, a map of concepts and their relationships.
- Logical schema, a map of entities and their attributes and relations
- Physical schema, a particular implementation of a logical schema
- Schema object, Oracle database object