WGU C175/D426 DATA MANAGEMENT FOUNDATIONS OA ACTUAL EXAM 2 LATEST VERSIONS 400 QUESTIONS AND CORRECT VERIFIED ANSWERS WITH RATIONALES (100% CORRECT) A+ GRADED ASSURED

WGU C175/D426 DATA MANAGEMENT FOUNDATIONS OA ACTUAL EXAM 2 LATEST VERSIONS 400 QUESTIONS AND CORRECT VERIFIED ANSWERS WITH RATIONALES (100% CORRECT) A+ GRADED ASSURED What does cardinality refer to? How does it appear on ER diagram? - ANSWER Refers to the MAXIMUM number of times an instance in one entity can be associated with instance of another entity (Maxima) Appears as a 1 or M on the relationship line, closest to entity What does modality refer to? How does it appear on ER diagram? - ANSWER Refers to the MINIMUM number of times an instance in one entity can be associated with instance of another entity (minima) Appears as a 0 or 1 on the relationship line, next to cardinality Define: Referential Integrity - ANSWER -Requires that ALL foreign key values must either be fully NULL or match some primary key value 4 Ways Referential Integrity can be violated: - ANSWER -1. Primary key is updated 2. Foreign key is updated 3. Row containing primary key is DELETED 4. Row containing foreign key is INSERTED 4 Actions to Correct Referential Integrity Violation: - ANSWER -1. RESTRICT - rejects an insert, update, or delete 2. SET NULL - sets invalid foreign keys to null 3. SET DEFAULT - sets invalid foreign keys to a default primary value 4. CASCADE - propagates primary key changes to foreign keys What is an important aspect to referential integrity? - ANSWER -reference to data in one relation is based on values in another relation What is a broad definition of data? - ANSWER -Raw facts captured on printed or digital media What are data? - ANSWER -Facts that are collected and stored in a database system What is a determining characteristic of unstructured data? - ANSWER -It does not follow a data model What is true about flat files? - ANSWER -- They contain no internal hierarchical organization How were data retrieved before database management systems? - ANSWER Sequentially from simple files What is an attribute or group of attributes that uniquely identify a tuple in a relation? - ANSWER -Primary Key What is necessary for a primary key in one relation of a database to match with its corresponding foreign key in another relation of the same database? - ANSWER A domain of values What uniquely identifies each entity in a collection of entities but is not the primary key? - ANSWER -Alternate Key What is the term for a set of columns in a table that can uniquely identify any record in that table without referring to other data? - ANSWER -Candidate Key What happens to the original data in database indexing? - ANSWER -It is copied to the index Why are indexes created in a physical database design? - ANSWER -To retrieve data DIRECTLY using a pointer Why is an index created on a database column? - ANSWER -To optimize data retrievals Define: Functional Dependency - ANSWER -Each value of a column relates to at MOST one value of another column Dependence of one column on another What term is used to describe: a value of one particular attribute associated with a specific single value of another attribute? - ANSWER -Functional Dependency Rules/Appearance of First Normal Form - ANSWER -- All non-key columns depend on primary key - Each table cell contains one value - A table with no duplicate rows Rules/Appearance of Second Normal Form - ANSWER -- When all non-key columns depend on the WHOLE primary key - Must be in 1NF - Non-key column can not depend on just one part of a composite key - a single primary key is automatically in 2NF Rules/Appearance of Third Normal Form - ANSWER -- All non-key columns depend ONLY on the primary key - Tables are totally free of data redundancy What are the 4 ways that operational and analytical databases differ? - ANSWER -- Volatility - Detail - Scope - History Define: Volatility; How it applies to Operational? Analytical? - ANSWER -- Database updates in real time - Operational Data is Volatile - Analytical Data is NOT Volatile Define: Detail; How it applies to operational and analytical DB? - ANSWER -- A database that keeps record of individual transactions; line items - Operational: Detailed - Analytical: Detailed Define: Scope; How it applies to operational and analytical DB? - ANSWER -- How far a database can reach - Operational: incompatible - Analytical: Enterprise-Wide/Summary Define: History; How it applies to operational and analytical DB? - ANSWER -- Whether DB is current or tracks all data