WGU C192 Data Management for Programmers Questions & Answers Solved 100% Correct!!

external schema - Answer-Also called a subschema, this is a specific view of the data utilized by an end user conceptual schema - Answer-This describes all the entities, attributes, and relationships together with integrity constraints. Each DB has exactly one. internal schema - Answer-A complete description of the internal model, down to the physical storage of data. Each DB has exactly one. logical data independence - Answer-The immunity of the external schemas to changes in the conceptual schema physical data independence - Answer-The immunity of the conceptual schema to changes in the internal schema data model - Answer-An integrated collection of concepts for describing and manipulating data, relationships between data, and constraints on the data in an organization (structural, manipulative, constraints) conceptual modeling - Answer-The process of constructing a detailed architecture for a database that is independent of implementation details logical modeling - Answer-The process of constructing a model of the data based on a specific data model, but that is independent of implementation details intension - Answer-Term for the structure of a relation/table, together with a specification of the domains and any other restrictions on possible values extension (state) - Answer-Term for the tuples of a relation, which change over time degree (relation) - Answer-Term for the number of attributes a relation/table containscardinality (relation) - Answer-Term for the number of tuples in a relation/table. Changes over time. superkey - Answer-An attribute, or set of attributes, that uniquely identifies a tuple within a relation candidate key - Answer-A superkey such that no proper subset is a superkey within the relation (atomic superkey) alternate keys - Answer-The candidate keys that are not selected to be the primary key entity integrity - Answer-In a base relation, no attribute of a primary key can be null referential integrity - Answer-If a foreign key exists in a relation, either the foreign key value must match a candidate key value of some tuple in its home relation or the foreign key value must be wholly null base relation - Answer-A named relation corresponding to an entity in the conceptual schema, whose tuples are physically stored in the database view - Answer-The dynamic result of one or more relational operations operating on the base relations to produce another relation; a virtual relation that does not necessarily exist in the database but can be produced upon request by a particular user, at the time of request closure - Answer-The property allowing expressions to be nested in the relational algebra, just as we can nest arithmetic operations selection (restriction) - Answer-Relational algebra operation that works on a single relation R and defines a relation that contains only those tuples of R that satisfy the specified condition (predicate) projection - Answer-Relational algebra operation that works on a single relation R and defines a relation that contains a vertical subset of R, extracting the values of specified attributes and eliminating duplicates (i.e., selecting specific columns from a table) union - Answer-Relational algebra operation that defines a relation that contains all the tuples of R, or S, or both R and S, duplicate tuples being eliminated. R and S must be rence - Answer-Relational algebra operation that defines a relati