Database Concepts Test Questions with Correct Answers Already Passed Graded A+
Redundancy - Answers the appearance of the same data factor in more than one field or table of data
Concurrency - Answers A condition in which two or more transactions are processed against the
database at the same time. In a single CPU system, the changes are interleaved; in a multi-CPU system,
the transactions may be processed simultaneously, and the changes on the database server are
interleaved.
Foreign Key - Answers A key that uniquely identifies a row in another table or the same table
Primary Key - Answers a candidate key selected to be the key of a relation
Surrogate Key - Answers A unique, system-supplied identifier used as the primary key of a relation. The
values of a surrogate key have no meaning to the users and usually, are hidden on forms and reports.
Attribute - Answers (1) A value that represents a characteristic of an entity. (2) A column of a relation
Composite Key - Answers A key of a relation that consists of two or more columns.
Referential Integrity Constraint - Answers A relationship constraint on foreign key values. A referential
integrity constraint specifies that the values of a foreign key must be a subset of the values of the
primary key to which it refers.
Relational Database - Answers A database that consists of relations. In practice, relational database
contain relations with duplicate rows. Most DBMS products include a feature that removes duplicate
rows when necessary and appropriate. Such removal is not done as a matter of course because it can be
time-consuming and expensive.
Structured Query Language (SQL) - Answers A language for defining the structure and processing of a
relational database. It can be used as a stand-alone query language, or it can be embedded in
application programs. SQL was developed by IBM and is accepted as a national standard by the
American National Standards Institute.
Data Warehouse - Answers A store of enterprise data that is designed to facilitate management decision
making. A data warehouse includes not only data but also metadata, tools, procedures, training,
personal information, and other resources that make access to the data easier and more relevant to
decision makers.
Database Administrator (DBA) - Answers A person or group responsible for establishing policies and
procedures to control and protect a database. They work within guidelines set by data administration to
control the database structure, manage data changes, and maintain DBMS programs
Database Management System (DBMS) - Answers A set of programs used to define, administer, and
process a database and its applications.
, data integrity - Answers The result of implementing domain integrity, entity integrity, and referential
integrity in a database.
Deletion Anomaly - Answers In a relation, the situation in which the removal of one row of a table
deletes facts about two or more themes.
Insertion Anomaly - Answers In a relation, the condition that exists when, to add a complete row to a
table, one must add facts about two or more logically different themes.
Update Anomaly - Answers An update anomaly is a data inconsistency that results from data
redundancy and a partial update
entity - Answers Something of importance to a user that needs to be represented in a database. In the
entity-relationship model, entities are restricted to things that can be represented by a single table
First Normal Form (1NF) - Answers Any table that fits the definition of a relation.
Second Normal Form (2NF) - Answers A relation in first normal form in which all non-key attributes are
fully dependent on all the keys.
Third Normal Form (3NF) - Answers A relation in second normal form that has no transitive
dependencies.
Multivalued Dependency - Answers A condition in a relation with three or more attributes in which
independent attributes appear to have relationships they do not have.
Partial Dependency - Answers nonprime attribute is functionally dependent on part of a candidate key.
(A nonprime attribute is an attribute that's not part of any candidate key.)
transitive dependency - Answers There is no non-key attribute determined by another non-key attribute.
In a relation having at least three attributes, such as R (A, B, C), the situation in which A determines B
and B determines C, but B does not determine A.
Relation - Answers A two-dimensional array that contains single-value entries and no duplicate rows.
The meaning of the columns is the same in every row. The order of the rows and columns is immaterial.
null value - Answers An attribute value that has never been supplied. Such values are ambiguous and
can mean the value is unknown, the value is not appropriate, or the value is known to be blank.
INNER JOIN, ON - Answers A relational algebra operation on two relations, A and B, that produces a third
relation, C. A row of A is concatenated with a row of B to form a new row in C if the rows in A and B
meet restrictions concerning their values.
LEFT JOIN - Answers The LEFT JOIN keyword returns all rows from the left table (table1), with the
matching rows in the right table (table2). The result is NULL in the right side when there is no match.
Redundancy - Answers the appearance of the same data factor in more than one field or table of data
Concurrency - Answers A condition in which two or more transactions are processed against the
database at the same time. In a single CPU system, the changes are interleaved; in a multi-CPU system,
the transactions may be processed simultaneously, and the changes on the database server are
interleaved.
Foreign Key - Answers A key that uniquely identifies a row in another table or the same table
Primary Key - Answers a candidate key selected to be the key of a relation
Surrogate Key - Answers A unique, system-supplied identifier used as the primary key of a relation. The
values of a surrogate key have no meaning to the users and usually, are hidden on forms and reports.
Attribute - Answers (1) A value that represents a characteristic of an entity. (2) A column of a relation
Composite Key - Answers A key of a relation that consists of two or more columns.
Referential Integrity Constraint - Answers A relationship constraint on foreign key values. A referential
integrity constraint specifies that the values of a foreign key must be a subset of the values of the
primary key to which it refers.
Relational Database - Answers A database that consists of relations. In practice, relational database
contain relations with duplicate rows. Most DBMS products include a feature that removes duplicate
rows when necessary and appropriate. Such removal is not done as a matter of course because it can be
time-consuming and expensive.
Structured Query Language (SQL) - Answers A language for defining the structure and processing of a
relational database. It can be used as a stand-alone query language, or it can be embedded in
application programs. SQL was developed by IBM and is accepted as a national standard by the
American National Standards Institute.
Data Warehouse - Answers A store of enterprise data that is designed to facilitate management decision
making. A data warehouse includes not only data but also metadata, tools, procedures, training,
personal information, and other resources that make access to the data easier and more relevant to
decision makers.
Database Administrator (DBA) - Answers A person or group responsible for establishing policies and
procedures to control and protect a database. They work within guidelines set by data administration to
control the database structure, manage data changes, and maintain DBMS programs
Database Management System (DBMS) - Answers A set of programs used to define, administer, and
process a database and its applications.
, data integrity - Answers The result of implementing domain integrity, entity integrity, and referential
integrity in a database.
Deletion Anomaly - Answers In a relation, the situation in which the removal of one row of a table
deletes facts about two or more themes.
Insertion Anomaly - Answers In a relation, the condition that exists when, to add a complete row to a
table, one must add facts about two or more logically different themes.
Update Anomaly - Answers An update anomaly is a data inconsistency that results from data
redundancy and a partial update
entity - Answers Something of importance to a user that needs to be represented in a database. In the
entity-relationship model, entities are restricted to things that can be represented by a single table
First Normal Form (1NF) - Answers Any table that fits the definition of a relation.
Second Normal Form (2NF) - Answers A relation in first normal form in which all non-key attributes are
fully dependent on all the keys.
Third Normal Form (3NF) - Answers A relation in second normal form that has no transitive
dependencies.
Multivalued Dependency - Answers A condition in a relation with three or more attributes in which
independent attributes appear to have relationships they do not have.
Partial Dependency - Answers nonprime attribute is functionally dependent on part of a candidate key.
(A nonprime attribute is an attribute that's not part of any candidate key.)
transitive dependency - Answers There is no non-key attribute determined by another non-key attribute.
In a relation having at least three attributes, such as R (A, B, C), the situation in which A determines B
and B determines C, but B does not determine A.
Relation - Answers A two-dimensional array that contains single-value entries and no duplicate rows.
The meaning of the columns is the same in every row. The order of the rows and columns is immaterial.
null value - Answers An attribute value that has never been supplied. Such values are ambiguous and
can mean the value is unknown, the value is not appropriate, or the value is known to be blank.
INNER JOIN, ON - Answers A relational algebra operation on two relations, A and B, that produces a third
relation, C. A row of A is concatenated with a row of B to form a new row in C if the rows in A and B
meet restrictions concerning their values.
LEFT JOIN - Answers The LEFT JOIN keyword returns all rows from the left table (table1), with the
matching rows in the right table (table2). The result is NULL in the right side when there is no match.
