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Is schema a logical structure or physical structure in oracle database?
the schema can be termed either conceptual or logical or physical. But mostly speaking, the term schema is used to refer to a logical structure.
What is a database schema?
A database schema is 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 Levels of database schema 1. Conceptual schema, a map of concepts and their relationships 2. Logical schema, a map of entities and their attributes and relations 3. Physical schema, a particular implementation of a logical schema 4. Schema object, Oracle database object 5. Schema is the over all structure of the database
What is Schema and instances?
In DBMS,Schema is the overall Design of the Database.Instance is the information stored in the Database at a particular moment.In programming,you declare a variable which corresponds to "Schema".But its values changes as and when required which corresponds to "Instance". Google about levels of Database Abstraction. 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.
What is schema instance?
In DBMS,Schema is the overall Design of the Database.Instance is the information stored in the Database at a particular moment.In programming,you declare a variable which corresponds to "Schema".But its values changes as and when required which corresponds to "Instance". Google about levels of Database Abstraction. 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.
What is the data schema in a database?
Logical Structure of database is know as database schema. All database entities are defined and relation between then is represented in structured way. It includes all constraints to be apply on each identity.
What do you mean by Schema in DBMS?
overall design of the database
What is logical data independence and its importance?
logical data independence 1)the ablity to modify the conceptual scheme without causing application program to be rewritten. 2)usually done when logical structure of database is altered. The logical data independence is the key side of database management system for maintaining data integrity and for maintain overall effectiveness of data usage. Logical data nouns is an important part of three schema architecture which allows the change or modification of conceptual schema short disturbing the external schema. The modifications in conceptual schema may include alteration of entities, attributes, relationships etc. Changing any of these elements will not disturb the external application programs which is a key advantage of logical information independence feature of database management systems.
What is the examples of three levels of schema?
Schemas can be classified into three levels: physical schema, logical schema, and view schema. The physical schema refers to the actual storage of data on hardware, detailing how data is stored in files and disks. The logical schema defines the structure of the database in terms of tables and relationships, abstracting away the physical details. Lastly, the view schema presents how data is seen and interacted with by users, often representing a subset or specific aspect of the logical schema tailored for particular applications or user roles.
What is schema object of database?
We know that schema in the database is refer to the basic design of that database and is stored in an object . That object is known as schema object of database.
What is the difference between schema and database?
Database schema are the logical structure of entities (tables or object classes) and their relationships (keys, or object associations) in a database. Schema can exist at different levels of abstraction (see: en.wikipedia.org/wiki/Database_schema). Schema themselves may or may not exist as such in a database. In general schema at the higher levels of abstraction are design models that are captured in printed documents, and authored by business analysts and database designers, rather than created by database programmers and stored in the database itself. But in some types of databases, schema at any level of abstaction can be realized physically. In Oracle databases, schema can be realized as schema objects, which are a part of an Oracle database. These schema objects may represent a human user's conceptual model of the knowledge captured in an enterprise database. Thus defined, there can be many schema that can be associated with one physical database. In other kinds of relational database, an abstract user's schema can be represented by logically linked metadata, views, and stored procedures assocated with a user class. In object-oriented databases, especially those based on the highly self-referential language Smalltalk (e.g. Gemstone/S), schema are realized as "physical" objects in the database as a matter of course, as well as in the logical models captured in design documents. The schema objects in such databases are, in essence, the classes comprising the infrastructure of the database or application. Oracle-style user schema are readily created; these would be realized as user interface orchestrator classes.
What is logical data independence and why is it important?
Logical data independence refers to the key feature of database management system that helps maintain data integrity and the overall effectiveness of the data usage. It is very important as it allows for the modification of the conceptual schema without disturbing the external schema.
What is a schema describes?
A schema describes the structure and organization of a database. It defines the tables, attributes, relationships, constraints, and data types that make up the database. It is like a blueprint that ensures data integrity and consistency.
