WGU D426 EXAM STUDY GUIDE 2026/2027
COMPLETE QUESTIONS WITH VERIFIED
CORRECT ANSWERS || 100%
GUARANTEED PASS <NEWEST VERSION>
A ____ is a column, or group of columns, used to identify a row. - ANSWER
Primary key
A ____ consists of a single column. - ANSWER Simple primary key
A ____ key consists of multiple columns. - ANSWER Composite primary
All primary keys columns are necessary for uniqueness. When any column is
removed, the resulting simple or composite column is no longer unique. -
ANSWER Minimal
The ____ constraint in the CREATE TABLE statement names the table's ____.
The ____ constraint ensures that a column or group of columns is always unique
and non-null. - ANSWER Primary key
An _____ is a numeric column that is assigned an automatically incrementing
value when a new row is inserted. - ANSWER Auto-increment column
The ____ keyword defines an auto-increment column. It follows the column's data
type in a CREATE TABLE statement. - ANSWER AUTO_INCREMENT
,A ____ is a column, or group of columns, that refer to a primary key. - ANSWER
Foreign key
____ requires foreign key values must either be NULL or match some value of the
referenced primary key. - ANSWER Referential integrity
A ____ constraint is added to a CREATE TABLE statement with the ____ and
REFERENCES keywords. - ANSWER Foreign key; references
A ____ foreign key is a simple or composite foreign key in which all columns are
NULL. - ANSWER Fully NULL
Data structures (Relational Model) - ANSWER prescribe how data is organized.
tuple (Relational Model) - ANSWER an ordered collection of elements enclosed
in parentheses. Ex: (a, b, c) and (c, b, a) are different, since tuples are ordered.
Rules (Relational Model) - ANSWER that govern valid data
table (Relational Model) - ANSWER has a name, a fixed tuple of columns, and a
varying set of rows.
column (Relational Model) - ANSWER has a name and a data type.
row (Relational Model) - ANSWER an unnamed tuple of values. Each value
corresponds to a column and belongs to the column's data type.
data type (Relational Model) - ANSWER a named set of values, from which
column values are drawn.
, Select (Relational Model) - ANSWER selects a subset of rows of a table.
(Relational operations)
Join (Relational Model) - ANSWER combines two tables by comparing related
columns. (Relational operations)
Union (Relational Model) - ANSWER selects all rows of two tables (Relational
operations)
Aggregate (Relational Model) - ANSWER perform a calculation on a set of values
and return a single result. They are commonly used to summarize or analyze data,
such as calculating sums, averages, counts, or finding maximum or minimum
values within a dataset. (Relational operations)
logical constraints (Relational Model) - ANSWER Rules that ensure data is valid
(Relational Rules)
Business rules (Relational Model) - ANSWER e based on business policy and
specific to a particular database.
Ex: PassportNumber values may not repeat in different Employee rows.
Structured Query Language (SQL) - ANSWER the standard language for
relational databases, and is commonly supported in non-relational databases.
Literals (SQL) - ANSWER Explicit values that are string, numeric, or binary.
Strings must be surrounded by single quotes or double quotes. Binary values are
represented with x'0' where the 0 is any hex value.
, Ex. 'String' "String" 123 x'0fa2'
Keywords (SQL) - ANSWER Words with special meaning
Ex. SELECT, FROM, WHERE
Identifiers (SQL) - ANSWER Objects from the database like tables, columns, etc.
Ex. City, Name, Population
Data Definition Language (DDL) (SQL) - ANSWER defines the structure of the
database.
Data Query Language (DQL) (SQL) - ANSWER retrieves data from the database.
Data Manipulation Language (DML) (SQL) - ANSWER manipulates data stored
in a database.
Data Control Language (DCL) (SQL) - ANSWER controls database user access.
Data Transaction Language (DTL) (SQL) - ANSWER manages database
transactions.
table (Tables) - ANSWER has a name, a fixed sequence of columns, and a varying
set of rows.
COMPLETE QUESTIONS WITH VERIFIED
CORRECT ANSWERS || 100%
GUARANTEED PASS <NEWEST VERSION>
A ____ is a column, or group of columns, used to identify a row. - ANSWER
Primary key
A ____ consists of a single column. - ANSWER Simple primary key
A ____ key consists of multiple columns. - ANSWER Composite primary
All primary keys columns are necessary for uniqueness. When any column is
removed, the resulting simple or composite column is no longer unique. -
ANSWER Minimal
The ____ constraint in the CREATE TABLE statement names the table's ____.
The ____ constraint ensures that a column or group of columns is always unique
and non-null. - ANSWER Primary key
An _____ is a numeric column that is assigned an automatically incrementing
value when a new row is inserted. - ANSWER Auto-increment column
The ____ keyword defines an auto-increment column. It follows the column's data
type in a CREATE TABLE statement. - ANSWER AUTO_INCREMENT
,A ____ is a column, or group of columns, that refer to a primary key. - ANSWER
Foreign key
____ requires foreign key values must either be NULL or match some value of the
referenced primary key. - ANSWER Referential integrity
A ____ constraint is added to a CREATE TABLE statement with the ____ and
REFERENCES keywords. - ANSWER Foreign key; references
A ____ foreign key is a simple or composite foreign key in which all columns are
NULL. - ANSWER Fully NULL
Data structures (Relational Model) - ANSWER prescribe how data is organized.
tuple (Relational Model) - ANSWER an ordered collection of elements enclosed
in parentheses. Ex: (a, b, c) and (c, b, a) are different, since tuples are ordered.
Rules (Relational Model) - ANSWER that govern valid data
table (Relational Model) - ANSWER has a name, a fixed tuple of columns, and a
varying set of rows.
column (Relational Model) - ANSWER has a name and a data type.
row (Relational Model) - ANSWER an unnamed tuple of values. Each value
corresponds to a column and belongs to the column's data type.
data type (Relational Model) - ANSWER a named set of values, from which
column values are drawn.
, Select (Relational Model) - ANSWER selects a subset of rows of a table.
(Relational operations)
Join (Relational Model) - ANSWER combines two tables by comparing related
columns. (Relational operations)
Union (Relational Model) - ANSWER selects all rows of two tables (Relational
operations)
Aggregate (Relational Model) - ANSWER perform a calculation on a set of values
and return a single result. They are commonly used to summarize or analyze data,
such as calculating sums, averages, counts, or finding maximum or minimum
values within a dataset. (Relational operations)
logical constraints (Relational Model) - ANSWER Rules that ensure data is valid
(Relational Rules)
Business rules (Relational Model) - ANSWER e based on business policy and
specific to a particular database.
Ex: PassportNumber values may not repeat in different Employee rows.
Structured Query Language (SQL) - ANSWER the standard language for
relational databases, and is commonly supported in non-relational databases.
Literals (SQL) - ANSWER Explicit values that are string, numeric, or binary.
Strings must be surrounded by single quotes or double quotes. Binary values are
represented with x'0' where the 0 is any hex value.
, Ex. 'String' "String" 123 x'0fa2'
Keywords (SQL) - ANSWER Words with special meaning
Ex. SELECT, FROM, WHERE
Identifiers (SQL) - ANSWER Objects from the database like tables, columns, etc.
Ex. City, Name, Population
Data Definition Language (DDL) (SQL) - ANSWER defines the structure of the
database.
Data Query Language (DQL) (SQL) - ANSWER retrieves data from the database.
Data Manipulation Language (DML) (SQL) - ANSWER manipulates data stored
in a database.
Data Control Language (DCL) (SQL) - ANSWER controls database user access.
Data Transaction Language (DTL) (SQL) - ANSWER manages database
transactions.
table (Tables) - ANSWER has a name, a fixed sequence of columns, and a varying
set of rows.
