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A subschema 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 subschemas for each schema.
The following are a few of the many reasons subschemas are used:
1 Subschemas 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.
2. Subschemas enhance security factors and prohibit data compromise.
3. Subschemas 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.
Schema Data Definition Language (DDL)The schema data definition language (DDL) is used for describing a database, which maybe shared by many programs written in many languages. This description is in terms of the names and characteristics of the data items, data aggregates, records, areas, and sets included in the database, and the relationships that exist and must be maintained between occurrences of those elements in the database.l Data item. A data item is an occurrence of the smallest unit of named data. It is represented in a database by a value.l Data aggregate.A data aggregate is an occurrence of a named collection of data items within a record. There are two kinds-vectors and repeating groups. A vector is a one-dimensional sequence of data items, all of which have identical characteristics. A repeating group is a collection of data that occurs a number of times within a record occurrence collection may consist of data items, vectors.repeating groups
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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.
What is difference between Schema and Subschema?
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.
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.
Explain the three schema architecture of DBMS?
Physical schema,logical schema and sub schemas
What do you mean by Schema in DBMS?
overall design of the database
What is sub schema?
The schema is the physical arrangement of the data as it appears in the DBMS. The sub-schema is the logical view of the data as it appears to the application program.
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
Difference between database schema and a database state in dbms?
The distinction between database schema and database state is very important. When we define a new database, we specify its database schema only to the DBMS. At this point, the corresponding database state is the empty state with no data. We get the initial state of the database when the database is first populated or loaded with the initial data. From then on, every time an update operation is applied to the database, we get another database state. At any point in time, the database has a current state. The DBMS is partly responsible for ensuring that every state of the database is a valid state-that is, a state that satisfies the structure and constraints specified in the schema. The DBMS stores the descriptions of the schema constructs and constraints-also called the meta-data-in the DBMS catalog so that DBMS software can refer to the schema whenever it needs to. The schema is sometimes called the intension, and a database state an extension of the schema.
What are the 3 views of dbms?
A Database has three views. The External Schema: What the end user sees. The Internal Schema: What the programmers of the program see. The Conceptual Schema: The basic plan of the database. Most of the time this is in paper form as a Conceptual Schema Diagram (CSD)
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.
What do you mean by degree in DBMS?
It is the number of attribute of its relation schema. Its is an association among two or more entities..
What is the Difference between relation schema and relation instance?
difference between relation sehema and relation instance in dbms
