Database Management System Questions and Answers

Answer: A

They are examples of RDBMS.

Oracle Database, MySQL and Microsoft Access are relational database management systems: they store data in tables of rows and columns, link tables through keys, and are queried with SQL.

They are not operating systems, which manage the computer's hardware (Windows, Linux), nor utility software such as antivirus or disk tools. 'Application software' is too broad; the specific class they belong to is RDBMS.

Answer: D

The right object is a Report.

In Microsoft Access, a report presents data from tables or queries in a formatted layout designed for printing, with headings, grouping, totals and page numbers.

A table stores the raw data. A query selects or calculates data from tables. A form is used to enter and view records on screen. None of these is designed for well-formatted printed output.

Answer: C

MS Access is a desktop database.

Microsoft Access keeps its tables, queries, forms and reports in a single file on the user's own computer (an .accdb file) and is meant for one user or a small workgroup. It is a relational database management system bundled with Microsoft Office.

A server database such as SQL Server or Oracle runs as a separate service that many clients connect to. A distributed database spreads one database across several sites. 'Network database' names an older data model built on linked records, not a description of Access.

Answer: B

The field is the primary key.

A primary key uniquely identifies each row of a table, so every value in it appears only once and it cannot be empty. Relationships between tables are built on it: another table stores the same value to point back to the row.

That pointing column in the other table is the foreign key, and its values may repeat, since many rows can refer to one parent. A composite key is a primary key made of two or more columns together, so no single column of it need be unique. 'Unit key' is not a standard database term.

Answer: A

Correct answer: Serializable schedule.

A precedence, or serialization, graph has a node per transaction and an edge for each conflicting pair. If the graph has no cycle the schedule is serializable; a cycle means it is not. Deadlock is detected with a different graph, the wait-for graph.

Answer: B

Correct answer: 3NF

This is the transitive dependency that third normal form forbids: a non-key attribute determining another non-key attribute. Second normal form removes only partial dependencies on part of a composite key, so the relation can satisfy 2NF and still fail here.

Answer: D

Correct answer: All of the above.

Selection can be pushed through any of the three set operations, since deciding whether a tuple satisfies a condition does not depend on which relation it came from:

\[ \sigma_\theta(R \cup S) = \sigma_\theta(R) \cup \sigma_\theta(S) \]

and the same holds for intersection and difference. Doing the selection first is what makes such transformations worth applying.

Answer: C

Correct answer: No partial FDs exist.

Second normal form requires that every non-key attribute depend on the whole of the primary key, so a dependency on only part of a composite key - a partial functional dependency - is what 2NF eliminates. Transitive dependencies are left to 3NF.

Answer: C

Correct answer: DDL

DROP removes a table, view or index - a change to the structure of the database - so it belongs to the Data Definition Language, alongside CREATE and ALTER.

Answer: C

Correct answer: idempotent

Recovery may be interrupted and restarted, so an undo or redo may be applied more than once to the same record. The operations are therefore written to be idempotent: applying them twice leaves the same result as applying them once.