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ISA 245 Exam 2 With 100% Correct And Verified Answers
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ISA 245 Exam 2 With 100% Correct And Verified Answers
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ISA 245 Exam 2 With 100% Correct AndVerified Answers 2024-2025
Boyce-Codd Normal Form (BCNF) - Correct Answer-A special type
of third normal form (3NF) in which every determinant is a
candidate key.
Candidate key - Correct Answer-An attribute, or combination of
attributes, that uniquely identifies a row in a relation.
Fourth Normal Form (4NF) - Correct Answer-In 3NF and contains
no multiple independent sets of multivalued dependencies.
surrogate key - Correct Answer-A system-assigned primary key,
generally numeric and auto-incremented.
De-normalization - Correct Answer-The process of splitting or
combining normalized relations into physical tables based on
affinity of use of rows and fields. (intentionally adds redundancy)
Why do we need to consider de-normalization? - Correct Answer-
improves query performance, processing speed, makes reports
easier
multivalued attribute - Correct Answer-An attribute that may take
on more than one value for a given entity (or relationship)
instance.
Data Definition Language (DDL) - Correct Answer-DBMS language
that builds the data dictionary, creates the database, describes
logical views, and specifies record or field security constraints
(ex. creating a table, creating a view, etc.)
Vendarsol
,Data Manipulation Language (DML) - Correct Answer-DBMS
language that changes database content, including data element
creations, updates, insertions, and deletions (SELECT, UPDATE,
INSERT, DELETE, COMMIT, ROLLBACK)
Can you update a constraint? - Correct Answer-NO! We must drop
the constraint and add a new one instead
Adding new constraints - Correct Answer-ALTER TABLE
tablename
ADD (constraint)
CHECK
Inserting a record - Correct Answer-INSERT INTO table VALUES()
rowid - Correct Answer-internally assigned by the system
DROP vs DELETE. - Correct Answer-DROP: DDL that affects the
schema and cannot be rolled back. Deletes the entire table!
DELETE: DML that affects the data only and can be rolled back.
Deletes only the contents of the table while maintaining the
structure
COUNT(*) vs COUNT - Correct Answer-Count
all values, including null
Count just the non-null values
disable - Correct Answer-make unable to
perform a certain action
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, entity supertype - Correct Answer-A generic
entity type that contains the common
characteristics of the entity subtypes.
entity subtype - Correct Answer-contain the
unique characteristics of each entity
entity supertype vs entity subtype - Correct
Answer-A subtype is the subset of the entity
supertype. The supertype is more common
characteristics and the subtype is more
unique characteristics
specialization hierarchy - Correct Answer-
based on grouping unique characteristics and
relationships of entity subtypes
entity cluster - Correct Answer-temporary
entity used to represent groups of related
entities and relationships within a database
model. ("virtual" or "abstract" -not a real
entity type in the final ERD)
Why do we sometimes need to use entity
cluster in an ER diagram? - Correct Answer-
simplifies the ERD and enhances its
readability
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