Schema & Instance
Schema
A schema is a description of the data interface to the database (i.e. how the data is organized).
Schema is the overall design of a database.
It is the skeleton structure of the database.
It represents the logical view of the entire database.
A schema contains schema objects:- table, columns, data types, foreign key, primary key, views, stored procedure, etc.
It represents database objects and relationships with visual diagrams.
It is designed by database designers to help programmers.
The process of database creation is called data modeling.
A schema diagram can display only some aspects of a schema like the name of record type, data type, and constraints. Other aspects can't be specified through the schema diagram.
Instance
A database instance is a database (real data) that conforms to a given schema.
Data at a particular moment of time is called the instance of the database.
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