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Database Schema and Database Instance




Database Schema and Database Instance - Relational Model (Part2)

Database Schema -

The Database Schema will look like this : Database Schema - Schema and Instance in Database
Before describing the Instance of Schema, let us define some terms -

Database Instance of Schema -

The instance of above Schema will look like this : Database Instance of Schema - - Schema and Instance in Database A database Schema can be divided into two categories - A database may also have several schemas at the view level called subschemas, that describe different views of the database.

SubSchemas -

Schema Construct -

A component of the schema or an object within the schema, e.g. PNAME, PRODUCT, PRICE etc.
Relational Schema Relational Instance
Table Abstraction Set of tuples
Schema is the overall Design of the Database. The actual content of the database or say the data at a particular instant is called the Instance of Schema.
Database Schemas will remain the same. Database instances tend to change with time.
Relational Schema is just like a framework. When the schema framework is filled in with data item values, it is referred as an instance of the schema.

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Relational Model (Part 1) Relational Model (Part-3)

 

 


Post date: 2015-07-30 09:00:10
Post date GMT: 2015-07-30 09:00:10
Post modified date: 2015-12-16 12:58:36
Post modified date GMT: 2015-12-16 12:58:36

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