FUNDAMENTALS OF COMPUTER

Detailed explanation-1: -The subschema defines the portion of the database “seen” by the application pro-grams that actually produce the desired information from the data within the database. A data manipulation language (DML) defines the environment in which data can be managed and is used to work with the data in the database.

Detailed explanation-2: -Subschema-A subset of a schema. The subschema defines the portion of the database as ―seen‖ by the application programs that use it. See also schema. Table-A (conceptual) matrix comprising intersecting rows (entities) and columns (attributes) that represent an entity set in the relational model.

Detailed explanation-3: -Subschema. A subschema provides a view of the database as seen by an application program. This view is often a subset of the complete schema definition. At runtime, a subschema provides the DBMS with a description of those portions of the database that are accessible to the application program.

Detailed explanation-4: -Sub schema It gives the users a window through which he/she can view only that part of the database which he wants. For example − Student table in a database the programmer can access all fields of table, but the user can access only two or three fields of it.

Detailed explanation-5: -A subschema is a set of Data Elements that belong to the composition of a Table. The use of subschemas provides a partial view of this data. For example, a Table represents the American states. You can define a telephone subschema that groups the data that is related to the telephone coding (city number and area code).