WGU D426 Section 2 Relational Databases questions
with verified answers
What are the three parts of the database model? Ans ✔✔-Data structures
that prescribe how data is organized.
Operations that manipulate data structures.
Rules that govern valid data.
What is a Set? Ans ✔✔-An unordered collection of elements enclosed in
braces. Ex: {a, b, c} and {c, b, a} are the same, since sets are not
ordered.
What is a Tuple? Ans ✔✔-An ordered collection of elements enclosed in
parentheses. Ex: (a, b, c) and (c, b, a) are different since tuples are
ordered.
What terms mean the same as table, column, row and data type in
mathematical terms? Ans ✔✔-Relation, attribute, tuple, and domain
What terms mean the same as table, column, row and data type in file
processing? Ans ✔✔-File, field, record, and data type
Relational algebra Ans ✔✔-Relational operations that generate a result
table from input tables
Select Ans ✔✔-selects a subset of rows of a table.
, Project Ans ✔✔-selects (or chooses) certain attributes discarding other
attributes
Product Ans ✔✔-lists all combinations of rows of two tables.
Join Ans ✔✔-combines two tables by comparing related columns.
Union Ans ✔✔-selects all rows of two tables.
Intersect Ans ✔✔-selects rows common to two tables.
Difference Ans ✔✔-selects rows that appear in one table but not another.
Rename Ans ✔✔-changes a table name.
Aggregate Ans ✔✔-computes functions over multiple table rows, such as
sum and count.
Relational rules Ans ✔✔-logical constraints that govern data in every
relational database e.g. unique primary key, unique column names, no
duplicate rows
Business rules Ans ✔✔-based on business policy and specific to a
particular database.
with verified answers
What are the three parts of the database model? Ans ✔✔-Data structures
that prescribe how data is organized.
Operations that manipulate data structures.
Rules that govern valid data.
What is a Set? Ans ✔✔-An unordered collection of elements enclosed in
braces. Ex: {a, b, c} and {c, b, a} are the same, since sets are not
ordered.
What is a Tuple? Ans ✔✔-An ordered collection of elements enclosed in
parentheses. Ex: (a, b, c) and (c, b, a) are different since tuples are
ordered.
What terms mean the same as table, column, row and data type in
mathematical terms? Ans ✔✔-Relation, attribute, tuple, and domain
What terms mean the same as table, column, row and data type in file
processing? Ans ✔✔-File, field, record, and data type
Relational algebra Ans ✔✔-Relational operations that generate a result
table from input tables
Select Ans ✔✔-selects a subset of rows of a table.
, Project Ans ✔✔-selects (or chooses) certain attributes discarding other
attributes
Product Ans ✔✔-lists all combinations of rows of two tables.
Join Ans ✔✔-combines two tables by comparing related columns.
Union Ans ✔✔-selects all rows of two tables.
Intersect Ans ✔✔-selects rows common to two tables.
Difference Ans ✔✔-selects rows that appear in one table but not another.
Rename Ans ✔✔-changes a table name.
Aggregate Ans ✔✔-computes functions over multiple table rows, such as
sum and count.
Relational rules Ans ✔✔-logical constraints that govern data in every
relational database e.g. unique primary key, unique column names, no
duplicate rows
Business rules Ans ✔✔-based on business policy and specific to a
particular database.
