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What is the difference between database instance and relation schema?
Database Instance The term instance is typically used to describe a complete database environment, including the RDBMS software, table structure, stored procedures and other functionality. It is most commonly used when administrators describe multiple instances of the same database.Also Known As: environment Examples: An organization with an employees database might have three different instances: production (used to contain live data), pre-production (used to test new functionality prior to release into production) and development (used by database developers to create new functionality). RELATION SCHEMA A relation schema can be thought of as the basic information describing a table or relation. This includes a set of column names, the data types associated with each column, and the name associated with the entire table. For example, a relation schema for the relation called Students could be expressed using the following representation: Students(sid: string, name: string, login: string, age: integer, gpa: real) There are five fields or columns, with names and types as shown above.
What is the difference between catalog schema and database in SQL Server?
A catalog is simple a group of related schema collected together in a defined namespace. While schema is a group of one or more related object collected in a common namespace.
What is the difference between data model and schema in database?
As I understand it, a database schema is a physical entity, it describes the structure of exactly how the data is stored and is itself stored by DBMS for reference. Data model, on the other hand, is an abstract representation of database.
What is the difference between relation and table in data base?
Table is where the data is stored and in a well designed schema a table represents some real world object such as CUSTOMER, ORDER, etc., Now the real world objects have relationships. For example, a CUSTOMER has many ORDERS. To represent this relationship a database relationship was invented.
What is the difference between derived attribute and normal attribute?
A normal attribute is an attribute present in a schema and which has to be entered while entering a tuple.A derived Attribute is one which can be inferred(derived) from another normal attribute and it need not be a part of a schema.For e.g.-> In a schema, Date-of-Birth is a normal attribute.While Age is a derived attribute which can be derived from the Date-of-Birth
