3. Define instances and schemas.
In DBMS, Instance is the information stored in the Database at a particular moment. Schema is the overall Design of the Database. In programming, we declare a variable which corresponds to “Schema”. But its values changes as and when required which corresponds to “Instance”.
Physical Schema describes database design at physical level while a logical schema describes the database design at the logical level. A database may also have several schemas at the view level, sometimes called subschemas, that describe different views of the database.