WGU D426 OA DATA MANAGEMENT FOUNDATIONS 2024
EXAM 400 COMPREHENSIVE QUESTIONS WITH DETAILED
VERIFIED ANSWERS /A+ GRADE ASSURED
Query Processor - (correct answer) Interprets queries. Compiles queries into low-level instructions
for the storage engine. Creates a plan to modify the database or retrieve data, and returns query results
to the application.
Query optimization - (correct answer) The query processor performs query optimization to ensure
the most efficient instructions are executed on the data.
Storage manager/engine - (correct answer) Translates the query processor instructions into low-
level file system commands that modify or retrieve data. Uses indexes to quickly locate data
Transaction manager - (correct answer) ensures transactions are properly executed. The
transaction manager prevents conflicts between concurrent transactions. The transaction manager also
restores the database to a consistent state in the event of a transaction or system failure.
CRUD - (correct answer) Create, Read, Update, Delete
Insert(create) inserts rows into a table
Select(read) retrieves data from a table
Update modifies data
Delete deletes rows
Analysis / Conceptual design - (correct answer) The analysis phase specifies database requirements
without regard to a specific database system.
Requirements are represented as entities, relationships, and attributes.
Logical desgin - (correct answer) The logical design phase implements database requirements in a
specific database system. For relational database systems, logical design converts entities,
relationships, and attributes into tables, keys, and columns.
Also called a schema
Physical design - (correct answer) The physical design phase adds indexes and specifies how tables
are organized on storage media. Physical design affects query processing speed but never affects the
query result.
Data independence - (correct answer) The principle that physical design never affects query results.
API (Application programming interface) - (correct answer) A library of procedures or classes that
links a host programming language to a database. Using one simplifies the use of SQL
MySQL Command-Line Client - (correct answer) a text interface included in the MySQL Server
download.
Set - (correct answer) An unordered collection of elements enclosed in braces {}
Tuple - (correct answer) is an ordered collection of elements enclosed in parentheses ()
Business rules - (correct answer) Based on business policy and specific to a particular database.
Relational rules govern data in all relational databases
, DDL - (correct answer) Data Definition Language (DDL) defines the structure of the database.
Controls tables. Includes CREATE, DROP, ALTER, TRUNCATE, RENAME
DQL - (correct answer) Data Query Language (DQL) retrieves data from the database. SELECT
DML - (correct answer) Data Manipulation Language (DML) manipulates data stored in a database.
Adds, modifies and deletes data. INSERT UPDATE DELETE
DCL - (correct answer) Data Control Language (DCL) controls database user access. Used to create
user accounts, manage permissions and access.
DTL - (correct answer) Data Transaction Language (DTL) manages database transactions. Can
rollback database changes
UPDATE - (correct answer) The UPDATE statement modifies existing rows in a table. The UPDATE
statement uses the SET clause to specify the new column values.
DELETE - (correct answer) The DELETE statement deletes existing rows in a table. The FROM
keyword is followed by the table name whose rows are to be deleted.
Primary key - (correct answer) A primary key is a column, or group of columns, used to identify a
row. The primary key is usually the table's first column. It is a simple primary key if it consists of a
single column
Composite primary key - (correct answer) A composite primary key consists of multiple columns.
Foreign key - (correct answer) A foreign key is a column, or group of columns, that refer to a
primary key.
Referential integrity - (correct answer) Referential integrity requires foreign key values must either
be NULL or match some value of the referenced primary key.
LIKE - (correct answer) The LIKE operator, when used in a WHERE clause, matches text against a
pattern using the two wildcard characters % and _.
INNER JOIN - (correct answer) selects only matching left and right table rows.
FULL JOIN - (correct answer) selects all left and right table rows, regardless of match.
LEFT JOIN - (correct answer) selects all left table rows, but only matching right table rows.
RIGHT JOIN - (correct answer) selects all right table rows, but only matching left table rows.
OUTER JOIN - (correct answer) is any join that selects unmatched rows, including left, right, and full
joins.
UNION - (correct answer) The UNION keyword combines the two results into one table.
Equijoin - (correct answer) An equijoin compares columns of two tables with the = operator. Most
joins are equijoins
Non-equijoin - (correct answer) compares columns with an operator other than =, such as < and >.
EXAM 400 COMPREHENSIVE QUESTIONS WITH DETAILED
VERIFIED ANSWERS /A+ GRADE ASSURED
Query Processor - (correct answer) Interprets queries. Compiles queries into low-level instructions
for the storage engine. Creates a plan to modify the database or retrieve data, and returns query results
to the application.
Query optimization - (correct answer) The query processor performs query optimization to ensure
the most efficient instructions are executed on the data.
Storage manager/engine - (correct answer) Translates the query processor instructions into low-
level file system commands that modify or retrieve data. Uses indexes to quickly locate data
Transaction manager - (correct answer) ensures transactions are properly executed. The
transaction manager prevents conflicts between concurrent transactions. The transaction manager also
restores the database to a consistent state in the event of a transaction or system failure.
CRUD - (correct answer) Create, Read, Update, Delete
Insert(create) inserts rows into a table
Select(read) retrieves data from a table
Update modifies data
Delete deletes rows
Analysis / Conceptual design - (correct answer) The analysis phase specifies database requirements
without regard to a specific database system.
Requirements are represented as entities, relationships, and attributes.
Logical desgin - (correct answer) The logical design phase implements database requirements in a
specific database system. For relational database systems, logical design converts entities,
relationships, and attributes into tables, keys, and columns.
Also called a schema
Physical design - (correct answer) The physical design phase adds indexes and specifies how tables
are organized on storage media. Physical design affects query processing speed but never affects the
query result.
Data independence - (correct answer) The principle that physical design never affects query results.
API (Application programming interface) - (correct answer) A library of procedures or classes that
links a host programming language to a database. Using one simplifies the use of SQL
MySQL Command-Line Client - (correct answer) a text interface included in the MySQL Server
download.
Set - (correct answer) An unordered collection of elements enclosed in braces {}
Tuple - (correct answer) is an ordered collection of elements enclosed in parentheses ()
Business rules - (correct answer) Based on business policy and specific to a particular database.
Relational rules govern data in all relational databases
, DDL - (correct answer) Data Definition Language (DDL) defines the structure of the database.
Controls tables. Includes CREATE, DROP, ALTER, TRUNCATE, RENAME
DQL - (correct answer) Data Query Language (DQL) retrieves data from the database. SELECT
DML - (correct answer) Data Manipulation Language (DML) manipulates data stored in a database.
Adds, modifies and deletes data. INSERT UPDATE DELETE
DCL - (correct answer) Data Control Language (DCL) controls database user access. Used to create
user accounts, manage permissions and access.
DTL - (correct answer) Data Transaction Language (DTL) manages database transactions. Can
rollback database changes
UPDATE - (correct answer) The UPDATE statement modifies existing rows in a table. The UPDATE
statement uses the SET clause to specify the new column values.
DELETE - (correct answer) The DELETE statement deletes existing rows in a table. The FROM
keyword is followed by the table name whose rows are to be deleted.
Primary key - (correct answer) A primary key is a column, or group of columns, used to identify a
row. The primary key is usually the table's first column. It is a simple primary key if it consists of a
single column
Composite primary key - (correct answer) A composite primary key consists of multiple columns.
Foreign key - (correct answer) A foreign key is a column, or group of columns, that refer to a
primary key.
Referential integrity - (correct answer) Referential integrity requires foreign key values must either
be NULL or match some value of the referenced primary key.
LIKE - (correct answer) The LIKE operator, when used in a WHERE clause, matches text against a
pattern using the two wildcard characters % and _.
INNER JOIN - (correct answer) selects only matching left and right table rows.
FULL JOIN - (correct answer) selects all left and right table rows, regardless of match.
LEFT JOIN - (correct answer) selects all left table rows, but only matching right table rows.
RIGHT JOIN - (correct answer) selects all right table rows, but only matching left table rows.
OUTER JOIN - (correct answer) is any join that selects unmatched rows, including left, right, and full
joins.
UNION - (correct answer) The UNION keyword combines the two results into one table.
Equijoin - (correct answer) An equijoin compares columns of two tables with the = operator. Most
joins are equijoins
Non-equijoin - (correct answer) compares columns with an operator other than =, such as < and >.
