SCHEMA is the physical arrangement of the data as it appears in the DBMS.
SUB-SCHEMA is the logical view of the data as it appears to the application program.
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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.
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.
difference between relation sehema and relation instance in dbms
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
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.
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.
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
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.
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.
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.
I think background knowledge is something you can build with a student, whereas schema is what they already have experienced. I'm studying this stuff in grad school, and I googled this trying to find an answer. I'm pretty certain that's essentially the difference. and also teacher can not provide students with schemata but can provide students with background knowledge.
In a relational database, the schema defines the tables, the fields in each table, and the relationships between fields and tables.