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What is schema and sub-schema?
The schema is the physical arrangement of the data as it appears in the DBMS. The subschema is the logical view of the data as it appears to the application program.
Why should a subschema be independent of schema?
A subschema should be independent of the schema to ensure modularity and reusability. This allows the subschema to be easily used in different contexts without being tightly coupled to any specific schema, providing flexibility and promoting code maintainability.
Why subschema is independent of schema?
A subschema is a subset of a larger schema, and it is designed to be independent and self-contained. It can exist and operate separately from the larger schema, providing specific functionality or representing a specific component of the overall schema. This independence allows for modular design and development, making it easier to manage and maintain the schema as a whole.
What is the Difference between relation schema and relation instance?
difference between relation sehema and relation instance in dbms
Difference between schema sub schema and instance in DBMS in detail?
the overall logical data base description is referred to as a schema. it is sometimes also referred to as an overall modal of the data, a conceptual modal of the data, a conceptual schema
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.
Why do you need mapping between schema levels?
There is need for mappings between schema levels for visualization and schema matching. The mappings between schema levels helps in the different types of transformation.
Difference between star flake schema and star schema?
STAR SCHEMA ::contains dimension tables mapped around a fact table. it is a de normalised model.no need to use complicated joins.queries results fastly. @ahsan_ravian@hotmail.com
Difference between user and schema for DB2?
In DB2, a user is an individual who is granted permissions to access and interact with the database, while a schema is a named collection of tables, views, procedures, and other database objects owned by a user. Users are associated with schemas to define their default schema for objects they create.
Difference between catalog and schema?
A catalog is a set of tables which contains the definitions or descriptions of the database structure and its constraints. For example it could store the structure of each file +Type and Format of each data item stored in the file. A catalog is a type of schema and a schema is what defines a data elements and their interrelationships.
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.
Description of database subschema?
What are the purpose of developing a sub-schema in database? In database management, the Subschema pronounced "sub-skee-mah." is an individual user's partial view of the database while the schema is the entire database. It is the applications programmer's view of the data within the database pertinent to the specific application. A subschema has access to those areas, set types, record types, data items, and data aggregates of interest in the pertinent application to which it was designed. Naturally, a software system usually has more than one programmer assigned and includes more than one application. This means there are usually many different sub schemas for each schema. The following are a few of the many reasons sub schemas are used: # Sub schemas provide different views of the data to the user and the programmer, who do not need to know all the data contained in the entire database. # Sub schemas enhance security factors and prohibit data compromise. # Sub schemas aid the DBA while assuring data integrity. Each data item included in the subschema will be assigned a location in the user working area (UWA). The UWA is conceptually a loading and unloading zone, where all data provided by the DBMS in response to a CALL for data is delivered. It is also where all data to be picked up by the DBMS must be placed.
