ADatabase Administrator (DBA)is responsible for the management, security, and performance of a database system. This includes controlling access to data, ensuring database integrity, optimizing performance, managing backups, and protecting the system from unauthorized access.
Option A (Incorrect):A DBA is not just a consumer of data but is primarily responsible for the database’s management.
Option B (Correct):Security is one of the key responsibilities of a DBA, including enforcing user access controls and implementing encryption and authentication mechanisms.
Option C (Incorrect):While DBAs work with data structures, it is typically the role of adata architectordatabase designerto define data formats and schema structures.
Option D (Incorrect):Developing application programs that interact with the database is typically the role ofsoftware developersordatabase programmers, not DBAs.
[Reference:Database Administration best practices from SE 3050 zyBooks., ]
Question 2
Which keyword can be used as a clause in an ALTER TABLE statement?
Options:
A.
DELETE
B.
CHANGE
C.
STOP
D.
AGGREGATE
Answer:
B
Explanation:
TheALTER TABLEstatement is used to modify an existing database table structure. One common clause isCHANGE, which allows renaming a column and modifying its data type.
Example:
sql
ALTER TABLE Employees CHANGE COLUMN OldName NewName VARCHAR(50);
Option A (Incorrect):DELETE is used to removerows, not alter table structure.
Option B (Correct):CHANGE is avalid clausefor renaming and modifying columns in MySQL and some other databases.
Option C (Incorrect):STOP is not a valid SQL keyword for altering tables.
Option D (Incorrect):AGGREGATE refers to functions like SUM() and AVG(), not table alterations.
[Reference:SQL ALTER TABLE syntax in SE 3050 zyBooks., ]
Question 3
What is the role of a query processor in the database system architecture?
Options:
A.
It uses information from the catalog to perform query optimization.
B.
It writes log records before applying changes to the database.
C.
It translates instructions into file system commands.
D.
It sends results back to the application that requested the queries.
Answer:
A
Explanation:
Aquery processoris responsible forquery optimization and executionin a database management system (DBMS). It analyzes SQL statements, optimizes execution plans, and ensures efficient retrieval of data.
Option A (Correct):Thequery processoroptimizes queries by analyzing metadata from thesystem catalogto determine the best execution strategy.
Option B (Incorrect):Logging transactionsbefore applying changes is the responsibility of thetransaction manager.
Option C (Incorrect):Translating instructions intofile system commandsis handled by thestorage manager, not the query processor.
Option D (Incorrect):While the query processor helps retrieve results, thedatabaseengineandAPI layerare responsible for returning results to applications.
[Reference:Query optimization and execution in relational databases., ]