preparation test exam with Thorough and
Correct answers Updated 2024/2025
COMMIT - correct answer The SQL command that permanently writes data changes to
a database.
COUNT - correct answer A SQL aggregate function that outputs the number of rows
containing not null values for a given column or expression, sometimes used in
conjunction with the DISTINCT clause.
CREATE INDEX - correct answer A SQL command that creates indexes on the basis
of a selected attribute or attributes.
CREATE TABLE - correct answer A SQL command that creates a table's structures
using the characteristics and attributes given.
DELETE - correct answer A SQL command that allows data rows to be deleted from a
table.
DISTINCT - correct answer A SQL clause that produces only a list of values that are
different from one another.
DROP INDEX - correct answer A SQL command used to delete database objects such
as tables, views, indexes, and users.
DROP TABLE - correct answer A SQL command used to delete database objects such
as tables, views, indexes, and users.
EXISTS - correct answer In SQL, a comparison operator that checks whether a
subquery returns any rows.
,FROM - correct answer A SQL clause that specifies the table or tables from which data
is to be retrieved.
GROUP BY - correct answer A SQL clause used to create frequency distributions
when combined with any of the aggregate functions in a SELECT statement.
HAVING - correct answer A clause applied to the output of a GROUP BY operation to
restrict selected rows.
IN - correct answer In SQL, a comparison operator used to check whether a value is
among a list of specified values.
inner query - correct answer A query that is embedded or nested inside another query.
Also known as a nested query or a subquery.
INSERT - correct answer A SQL command that allows the insertion of one or more
data rows into a table.
International Organization for Standardization (ISO) - correct answer An organization
formed to develop standards for diverse network systems.
IS NULL - correct answer In SQL, a comparison operator used to check whether an
attribute has a value.
LIKE - correct answer In SQL, a comparison operator used to check whether an
attribute's text value matches a specified string pattern.
MAX - correct answer A SQL aggregate function that yields the maximum attribute
value in a given column.
message - correct answer In the OO data model, the name of a method sent to an
object in order to perform an action. A message triggers the object's behavior. See
method.
, method - correct answer In the object-oriented data model, a named set of instructions
to perform an action. Methods represent real-world actions, and are invoked through
messages.
middleware - correct answer The computer software that allows clients and servers to
communicate within the client/server architecture. It is used to insulate client processes
from the network protocols and the details of the server process protocols.
MIN - correct answer A SQL aggregate function that yields the minimum attribute value
in a given column.
nested query - correct answer In SQL, a query that is embedded in another query. See
subquery.
NOT - correct answer A SQL logical operator that negates a given predicate.
OR - correct answer The SQL logical operator used to link multiple conditional
expressions in a WHERE or HAVING clause. It requires only one of the conditional
expressions to be true.
ORDER BY - correct answer A SQL clause that is useful for ordering the output of a
SELECT query (for example, in ascending or descending order).
recursive query - correct answer A nested query that joins a table to itself.
reserved words - correct answer Words used by a system that cannot be used for any
other purpose. For example, in Oracle SQL, the word INITIAL cannot be used to name
tables or columns.
ROLLBACK - correct answer A SQL command that restores the database table
contents to the condition that existed after the last COMMIT statement.
rules of precedence - correct answer Basic algebraic rules that specify the order in
which operations are performed. For example, operations within parentheses are