WGU D427 DATA APPLICATIONS
CERTIFICATION 2026 TEST PAPER
QUESTIONS AND ANSWERS GRADED A+
⩥ Relational Rules/Integrity Rules. Answer: Logical constraints that
ensure data is valid and conforms to business policy. Governs the data.
⩥ Structural Rules. Answer: Relational rules that govern data in every
relational database.
⩥ Business Rules. Answer: Relational rules specific to a particular
database AND application. Discovered during database design.
⩥ Table. Answer: A collection of data organized as columns and rows.
Has a name, a fixed sequence of columns, and a varying set of rows.
⩥ Column. Answer: Has a name and a data type.
⩥ Row. Answer: An unnamed sequence of values. Each value
corresponds to a column and belongs to the column's data type.
⩥ Cell. Answer: A single column of a single row. In relational databases,
each contains exactly one value.
,⩥ Aggregate. Answer: Computes functions over multiple table rows,
such as SUM and COUNT.
⩥ Join. Answer: A SELECT statement that combines data from two
tables (left and right), into a single result. The tables are combined by
comparing columns from the left and right tables.
⩥ Data Query Language (DQL). Answer: What language am I?
Retrieves data from the database.
⩥ Data Transaction Language (DTL). Answer: What language am I?
Manages database transactions.
⩥ Database System Instance. Answer: A single executing copy of a
database system. Personal computers usually run just one.
⩥ DROP TABLE. Answer: This statement deletes a table, along with all
the table's rows, from a database.
⩥ Operator. Answer: A symbol that computes a value from one or more
other values called operands.
, ⩥ Unary. Answer: Operator that has ONE operand.
⩥ Binary. Answer: Operator that has TWO operands.
⩥ Condition. Answer: An expression that evaluates to a logical value.
⩥ NULL. Answer: Special value that represents either UNKNOWN or
inapplicable data. Not the same as zero.
⩥ TRUNCATE. Answer: Deletes ALL ROWS from a table.
⩥ MERGE. Answer: Selects data from one table, called the source, and
inserts the data to another table, called the target. If the primary keys of
source and target rows match, the target values are updated to the
corresponding values.
⩥ Primary Key. Answer: A column, or group of columns, used to
identify a row. Usually the table's FIRST column.
⩥ Simple Primary Key. Answer: Consists of a single column.
CERTIFICATION 2026 TEST PAPER
QUESTIONS AND ANSWERS GRADED A+
⩥ Relational Rules/Integrity Rules. Answer: Logical constraints that
ensure data is valid and conforms to business policy. Governs the data.
⩥ Structural Rules. Answer: Relational rules that govern data in every
relational database.
⩥ Business Rules. Answer: Relational rules specific to a particular
database AND application. Discovered during database design.
⩥ Table. Answer: A collection of data organized as columns and rows.
Has a name, a fixed sequence of columns, and a varying set of rows.
⩥ Column. Answer: Has a name and a data type.
⩥ Row. Answer: An unnamed sequence of values. Each value
corresponds to a column and belongs to the column's data type.
⩥ Cell. Answer: A single column of a single row. In relational databases,
each contains exactly one value.
,⩥ Aggregate. Answer: Computes functions over multiple table rows,
such as SUM and COUNT.
⩥ Join. Answer: A SELECT statement that combines data from two
tables (left and right), into a single result. The tables are combined by
comparing columns from the left and right tables.
⩥ Data Query Language (DQL). Answer: What language am I?
Retrieves data from the database.
⩥ Data Transaction Language (DTL). Answer: What language am I?
Manages database transactions.
⩥ Database System Instance. Answer: A single executing copy of a
database system. Personal computers usually run just one.
⩥ DROP TABLE. Answer: This statement deletes a table, along with all
the table's rows, from a database.
⩥ Operator. Answer: A symbol that computes a value from one or more
other values called operands.
, ⩥ Unary. Answer: Operator that has ONE operand.
⩥ Binary. Answer: Operator that has TWO operands.
⩥ Condition. Answer: An expression that evaluates to a logical value.
⩥ NULL. Answer: Special value that represents either UNKNOWN or
inapplicable data. Not the same as zero.
⩥ TRUNCATE. Answer: Deletes ALL ROWS from a table.
⩥ MERGE. Answer: Selects data from one table, called the source, and
inserts the data to another table, called the target. If the primary keys of
source and target rows match, the target values are updated to the
corresponding values.
⩥ Primary Key. Answer: A column, or group of columns, used to
identify a row. Usually the table's FIRST column.
⩥ Simple Primary Key. Answer: Consists of a single column.
