DBMS - FINAL EXAM QUESTIONS AND ANSWERS
What is the purpose of a database, and how does the database accomplish this
purpose? - Answers -The purpose of a database is to help people keep track of things.
It accomplishes this purpose by storing data in tables. Each table has rows and
columns, like a spreadsheet. A database usually has multiple tables to keep track of
different by related things.
What are the four components of a database system? - Answers -The four components
in a database system are: the user, the database application, the database
management system (DBMS) and the database. The user interacts with the database
application, which interacts with the DBMS, which controls the database. The functions
of the database application include creating and processing forms, creating and
transmitting queries and creating and processing reports. The DBMS creates
databases, tables and supporting structures, manages database data, enforces rules
and provides security. The database stores the user data, the database metadata,
indexes, triggers, stored procedures and application metadata.
Briefly describe the function of an application program in a database system. - Answers
-The application program is responsible for creating and processing forms. The
application displays the form to the user, allows the user to complete the data entry,
evaluates the form to determine which data management tasks need to be performed,
and transmits the appropriate requests to the DBMS. The application creates and
transmits queries. The queries are requests for data that are created in a language like
SQL, and transmitted to the DBMS to have the requested data returned to the
application program. The application also creates and processes reports. The query to
retrieve the necessary data for the report is sent to the DBMS. When the DBMS returns
the needed data, the application manipulates it as necessary to create the requested
report. The application program also applies application logic to control the manipulation
of data in accordance with the business rules. Finally, the application program is
responsible for providing control. Control must be exercised to allow the users to make
choices for functions and tasks as appropriate for their jobs. Also, control must be
exercised to manage the activities of the DBMS.
What components are included in a database? - Answers -The database contains user
data, metadata, indexes and other overhead data, and application metadata. User data
is the data from the user's environment that they want to track. Metadata is data about
the structure of the database. Indexes and other overhead data are structures that the
database uses to improve performance. Finally, the application metadata is data about
forms, reports, and other application components that some databases, particularly
those created with desktop DBMS products, store with the database.
Why do we say a database is self-describing and why is this an advantage? - Answers
-A database is considered self-describing because it contains a description of its own
structure within the database itself. This description is called the metadata, and it is
, stored in specialized tables in relational databases. The advantage is that the database
is self-documenting, and that a knowledgeable user or a database designer can easily
access the metadata. All DBMS vendors provide tools to access the metadata within
their products.
What is metadata and how does it relate to the definition of a database? - Answers -
Metadata is data about the structure of the database itself. This includes data about the
names of all the tables in the database, the names of all the columns in each of the
tables, the data type of each column in each table, the properties of the tables and the
columns, etc. Metadata accounts for the self-describing aspect of the definition of a
database as a "self-describing collection of integrated tables."
Briefly describe the function of the DBMS in a database system. - Answers -The DBMS
creates the database and the tables and structures within it. The DBMS also reads and
updates the database data. It receives requests from application programs to perform
data maintenance tasks. These requests are translated into actions that are performed
on the database. In addition to maintaining the user data within the database, the DBMS
also maintains the database structures. The DBMS also enforces any rules that have
been defined to govern the values of the data, such as data type requirements and
referential integrity constraints. The DBMS controls concurrency issues, which deal with
the unwanted interruption of one user's work by another user's work. As the only point
of entry into the database, the DBMS also provides security for the database to restrict
users' access to only the data that they have authority to read or modify. Finally, the
DBMS is responsible for the creation of backup copies of the database data and for
restoring the database in case a recovery is required.
What are referential integrity constraints? Give an example. - Answers -A referential
integrity constraint is a rule that restricts certain actions on the database data. A
referential integrity constraint is used to ensure that the values in a field in one table
have matching tables in a corresponding field in another table. These constraints are
enforced by the DBMS, which will not allow changes to the values of the database that
would result in violations of this rule.
What are the three types of database design situations? - Answers -Database designs
can be based on (1) existing data, (2) new systems development and (3) database
redesign. Database designs from existing data may be based on data in spreadsheets
or other data tables, or on data extracted from other databases. New systems
development gathers user requirements for needed applications and designs a
database to meet those requirements. Database redesign may be needed to migrate
existing databases to a newer DBMS, or to integrate multiple existing databases.
Briefly describe the history of database processing. - Answers -The predecessor of
database processing was file processing, where data were maintained on magnetic
tape. Database processing as we know it today became possible with the availability of
direct access disk storage in the 1960s. Using this storage, both the hierarchical data
model and then the network data model were developed. In 1970, E. F. Codd of IBM
What is the purpose of a database, and how does the database accomplish this
purpose? - Answers -The purpose of a database is to help people keep track of things.
It accomplishes this purpose by storing data in tables. Each table has rows and
columns, like a spreadsheet. A database usually has multiple tables to keep track of
different by related things.
What are the four components of a database system? - Answers -The four components
in a database system are: the user, the database application, the database
management system (DBMS) and the database. The user interacts with the database
application, which interacts with the DBMS, which controls the database. The functions
of the database application include creating and processing forms, creating and
transmitting queries and creating and processing reports. The DBMS creates
databases, tables and supporting structures, manages database data, enforces rules
and provides security. The database stores the user data, the database metadata,
indexes, triggers, stored procedures and application metadata.
Briefly describe the function of an application program in a database system. - Answers
-The application program is responsible for creating and processing forms. The
application displays the form to the user, allows the user to complete the data entry,
evaluates the form to determine which data management tasks need to be performed,
and transmits the appropriate requests to the DBMS. The application creates and
transmits queries. The queries are requests for data that are created in a language like
SQL, and transmitted to the DBMS to have the requested data returned to the
application program. The application also creates and processes reports. The query to
retrieve the necessary data for the report is sent to the DBMS. When the DBMS returns
the needed data, the application manipulates it as necessary to create the requested
report. The application program also applies application logic to control the manipulation
of data in accordance with the business rules. Finally, the application program is
responsible for providing control. Control must be exercised to allow the users to make
choices for functions and tasks as appropriate for their jobs. Also, control must be
exercised to manage the activities of the DBMS.
What components are included in a database? - Answers -The database contains user
data, metadata, indexes and other overhead data, and application metadata. User data
is the data from the user's environment that they want to track. Metadata is data about
the structure of the database. Indexes and other overhead data are structures that the
database uses to improve performance. Finally, the application metadata is data about
forms, reports, and other application components that some databases, particularly
those created with desktop DBMS products, store with the database.
Why do we say a database is self-describing and why is this an advantage? - Answers
-A database is considered self-describing because it contains a description of its own
structure within the database itself. This description is called the metadata, and it is
, stored in specialized tables in relational databases. The advantage is that the database
is self-documenting, and that a knowledgeable user or a database designer can easily
access the metadata. All DBMS vendors provide tools to access the metadata within
their products.
What is metadata and how does it relate to the definition of a database? - Answers -
Metadata is data about the structure of the database itself. This includes data about the
names of all the tables in the database, the names of all the columns in each of the
tables, the data type of each column in each table, the properties of the tables and the
columns, etc. Metadata accounts for the self-describing aspect of the definition of a
database as a "self-describing collection of integrated tables."
Briefly describe the function of the DBMS in a database system. - Answers -The DBMS
creates the database and the tables and structures within it. The DBMS also reads and
updates the database data. It receives requests from application programs to perform
data maintenance tasks. These requests are translated into actions that are performed
on the database. In addition to maintaining the user data within the database, the DBMS
also maintains the database structures. The DBMS also enforces any rules that have
been defined to govern the values of the data, such as data type requirements and
referential integrity constraints. The DBMS controls concurrency issues, which deal with
the unwanted interruption of one user's work by another user's work. As the only point
of entry into the database, the DBMS also provides security for the database to restrict
users' access to only the data that they have authority to read or modify. Finally, the
DBMS is responsible for the creation of backup copies of the database data and for
restoring the database in case a recovery is required.
What are referential integrity constraints? Give an example. - Answers -A referential
integrity constraint is a rule that restricts certain actions on the database data. A
referential integrity constraint is used to ensure that the values in a field in one table
have matching tables in a corresponding field in another table. These constraints are
enforced by the DBMS, which will not allow changes to the values of the database that
would result in violations of this rule.
What are the three types of database design situations? - Answers -Database designs
can be based on (1) existing data, (2) new systems development and (3) database
redesign. Database designs from existing data may be based on data in spreadsheets
or other data tables, or on data extracted from other databases. New systems
development gathers user requirements for needed applications and designs a
database to meet those requirements. Database redesign may be needed to migrate
existing databases to a newer DBMS, or to integrate multiple existing databases.
Briefly describe the history of database processing. - Answers -The predecessor of
database processing was file processing, where data were maintained on magnetic
tape. Database processing as we know it today became possible with the availability of
direct access disk storage in the 1960s. Using this storage, both the hierarchical data
model and then the network data model were developed. In 1970, E. F. Codd of IBM
