er the statement is true (T) or false (F). __ Each Database Management System (DBMS) is based on a Data Model. __ Database Users may desire to perform conflicting operations at the same time. For example, in an Airline Reservation System, two on-line users may see the last empty seat while trying to reserve a seat on a flight. Concurrency features of a DBMS prevents them from reserving the same seat, therefore avoiding inconsistent database states. ___ In the Entity-Relationship Model (E-R), an Attribute maps an entity to another entity (or a set of entities). A Relationship, on the other hand, maps an entity to a primitive value. __ Specialization ISA is the result of taking the union of two or mo
For each item below, specify whether the statement is true (T) or false (F).
__ Each
__ Database Users may desire to perform conflicting operations at the same time. For example, in an Airline Reservation System, two on-line users may see the last empty seat while trying to reserve a seat on a flight. Concurrency features of a DBMS prevents them from reserving the same seat, therefore avoiding inconsistent database states.
___ In the Entity-Relationship Model (E-R), an Attribute maps an entity to another entity (or a set of entities). A Relationship, on the other hand, maps an entity to a primitive value.
__ Specialization ISA is the result of taking the union of two or more lower-level entity sets to produce a higher-level entity set. It emphasizes the similarity.
__ In the Network Data Model, relationships between record types are implemented by means of Link Types. Since there can be only one Link Type between two Record Types, we do not need to name the Link Types.
___ In the Hierarchical Data Model, AA and many-to-many Link Types are forbidden.
___ In the Hierarchical Data Model, each Record Type has one or more Children Record Types.
___ In the Relational Data Model, the order of attributes is not important.
___ In the Relational Data Model, Referential Integrity Constraint is a special kind/case of Foreign Key Constraint.
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