Questions and Answers of Principles Of Database Management

Consider the following query:The query retrieves:a. The number and name of all the products with no outstanding order.b. The number and name of all the products that are ordered.c. The query will
Consider the following query:The query retrieves:a. The name, number, and total outstanding orders of all suppliers that have outstanding orders.b. The name, number, and total outstanding orders of
Consider the following SQL query:This query selects:a. The five highest product numbers.b. The five lowest product numbers.c. All product numbers except for the five lowest product numbers.d. All
Write an SQL query using EXISTS to retrieve the supplier name and number of the supplier who has the lowest supplier number.
Why is it important that a DBMS has a good query optimizer?
Which statement(s) is/are correct? Statement A: There is no query processor available in procedural DML. Statement B: With procedural DML, the DBMS determines the access path and navigational
Give some examples of DBMS utilities and interfaces.
Evaluate the following statements:1. Record-at-a-time DML means that the query gets recorded from the user at the time the user inputs the query and then gets processed.2. Record-at-a-time DML
How can DBMSs be categorized in terms of the following?• Data model• Degree of simultaneous access• Architecture• Usage
Which statement(s) is/are correct? Statement A: The impedance mismatch problem can be solved by using middleware to map data structures between the DBMS and the DDL statements. Statement B: An
Which statement(s) is/are correct? Statement A: The query parser optimizes and simplifies a query and then passes it on to the query executor. Statement B: In the DBMS architecture, the storage
Fill in the gaps in the following sentences: When, during crash recovery, aborted transactions need to be undone, that is a task of the …A…The part of the storage manager that guarantees the ACID
CODASYL is an example of …a. A hierarchical DBMS.b. A network DBMS.c. A relational DBMS.d. An object-oriented DBMS.
Which of the following DBMS types is not a classification based on a data model?a. Hierarchical DBMS.b. Network DBMS.c. Cloud DBMS.d. Object-relational DBMS.
Which statement(s) is/are correct?Statement A: In a hierarchical DBMS, DML is declarative and set oriented with a query processor. Statement B: In a relational DBMS, there is data independence
If you want to use a DBMS architecture that can access multiple data sources itself and provides a uniform interface hiding the low-level details, the most appropriate DBMS would be a(n)…a. N-tier
Which statement(s) is/are correct? Statement A: An OLTP system is able to cope with real-time, simultaneous transactions that the database server is able to process in a large volume. Statement B: An
Which statement is not correct?a. The file-based approach to data management causes the same information to be stored separately for different applications.b. In a file-based approach to data
Discuss examples of database applications.
Which statement is not correct?a. In a database approach, applications don’t have their own files, but all applications access the same version of the data by interfacing with the DBMS.b. In a
What are the key differences between the file-based and database approaches to data management?
Which statement is not correct?a. In a file-based approach, every application has its own query and access procedures, even if they want to access the same data.b. SQL is a database language to
Discuss the elements of a database system
Which statement is not correct?a. In a conceptual data model, the data requirements from the business should be captured and modeled.b. A conceptual data model is implementation-dependent.c. A
What are the advantages of database systems and database management?
Complete the following sentence, choosing the right words in positions A andB. A(n) …A… data model is the mapping of a(n) …B… data model to a model that describes which data are stored where
What concept specifies the various data items, their characteristics, and relationships, constraints, storage details, etc. and is specified during the database design?a. Database
Which statement regarding the database state is correct?a. The database state represents the data in the database when the database is first created.b. The database state changes when data are
Which statement is correct? Statement A: The middle layer of the three-layer architecture consists of both the conceptual data model and the logical data model. The logical data model is physically
Complete this sentence: In the three-layer architecture, between the external layer and the conceptual/logical layer, there is …a. Physical data independence.b. Logical data independence.c. No
Which statement is correct? Statement A: DDL is the language used to define the logical data model, but no other data models. Statement B: SQL is a DML language to retrieve, insert, delete, and
Which statement is correct? Statement A: Physical data independence implies that neither the applications nor the views or logical data model must be changed when changes are made to the data storage
Discuss various strategies to ensure object persistence. When would you use what strategy? What are the key properties a persistence environment should support?
In Java, what is method overloading?a. Putting so much code in a method that its functionality becomes hard to understand.b. Using two methods with the same name, but a different number (and/or
What are object identifiers? Why are they used by OODBMSs? What is the difference with primary keys in an RDBMS?
a. Dynamic binding means that objects are allowed to take the form of either the class they are an instance of, or any of its subclasses.b. In an inheritance structure with a parent class
What are literals in the ODMG model? What types of literals are supported? How are literals mapped in Java? Illustrate with examples.
Objects should be made persistent when…a. You need them over multiple program executions.b. You only need them during one program execution, and then never again.
What types of relationships and cardinalities are supported in ODMG?
Which statement is not correct?a. Persistence by marking implies that all objects will be created as persistent. An object can then be marked as transient at compile time.b. Persistence by class
Contrast OQL with SQL.
Which statement about object identifiers (OIDs) is correct?a. The OID of an object remains the same during the entire lifetime of the object.b. An OID is the same as a primary key in a relational
Explain the following query in detail.How would you solve a similar query in SQL? SELECT e1.ENAME, e1.age, d.DNAME, e2.ENAME, e2.age FROM employees e1, el.works_in d, d.managed_by e2 WHERE el.age >
Which of the following statements about ODL is correct?a. ODL is only optimized for Java objects.b. The extent of a class is the set of all current instances.c. Many-to-many relationships cannot
Contrast OODBMSs versus RDBMSs in terms of:• Handling of complex objects;• Query performance;• Implementation of the three-layer database architecture;• Adoption in industry.
What statement about OQL is not correct?a. OQL is a declarative, non-procedural query language.b. Join queries are not supported in OQL.c. OQL can be used for both navigational (procedural) as
What is not an advantage of OODBMSs?a. They allow storing objects and relationships in a transparent way.b. They solve the impedance mismatch problem by using the same data model as the programming
Which statement is correct?a. In the relational model, the tuple constructor can only be used on atomic values and the set constructor can only be used on tuples.b. In the relational model, the
Give some examples of triggers and stored procedures for the purchase order database we discussed in Chapter 6. Discuss the advantages and disadvantages of both extensions.
Which of the following is not an advantage of triggers?a. Triggers support automatic monitoring and verification in case of specific events or situations.b. Triggers allow avoidance of deadlock
Contrast an ORDBMS against• An RDBMS;• An OODBMS.Give examples of applications where each of these can be used.
The key difference between stored procedures and triggers is that:a. Stored procedures are explicitly invoked whereas triggers are implicitly invoked.b. Stored procedures cannot have input
Which of the following is correct?a. A distinct data type is a user-defined data type which specializes a standard, built-in SQL data type.b. An opaque data type is an entirely new, user-defined
What are the different types of UDTs that can be supported by ORDBMSs? Illustrate with examples.
Which of the following is correct?a. User-defined functions (UDFs) can only work on user-defined data types.b. A sourced function is a user-defined function (UDF) that is based on an existing,
What are the different types of UDFs that can be supported by ORDBMSs? Illustrate with examples.
An ORDBMS will typically support inheritance…a. Only at tuple level.b. Only at data type level.c. Only at table type level.d. At both data type and table type level.
Consider a table hierarchy with supertable STUDENT and subtables BACHELOR_STUDENT, MASTER_STUDENT and PHD_STUDENT. Both bachelor and master students pass when they achieve at least 50%. PhD students
Which of these statements is correct?a. A set is an ordered collection with no duplicates.b. A bag is an unordered collection which may contain duplicates.c. A list is an ordered collection which
Which data type can be used to store image data?a. BLOB.b. CLOB.c. DBCLOB.d. None of the above.
How are large objects handled by ORDBMSs? Illustrate with examples.
Recursive queries are a powerful SQL extension which allow formulation of complex queries such as…a. Queries that need to combine data from multiple tables.b. Queries that need to get access to
Discuss how triggers, stored procedures, object-relational extensions, and recursive queries are supported in modern-day DBMSs provided by, e.g., Oracle, IBM, and Microsoft.
In industry, ORDBMSs have…a. Been very successful since they replaced RDBMSs as the mainstream database technology.b. Had modest success, with most companies only implementing a carefully
Consider the following relational model:COURSE(coursenr, coursename, profnr) – profnr is a foreign key referring to profnr in PROFESSORPROFESSOR(profnr, profname)PRE-REQUISITE(coursenr,
Consider our purchase order administration example from Chapter 3. Remember, a purchase order can have multiple purchase order lines, each corresponding to a particular product. A purchase order is
XML focuses on the…a. Content of documents.b. Representation of documents.
Using the purchase order example of Question 1, illustrate how the DOM and SAX APIs would process the XML document differently.Question 1Consider our purchase order administration example from
Which statement is correct?a. Using XSLT, an XML document can be transformed to another XML document.b. Using HTML, an XML document can be transformed to an XSLT document.c. Using XML, an XSLT
Discuss and contrast the various approaches that can be used to search XML data.
Which of the following statements about XML Schema is not correct?a. It is more verbose than DTD.b. It allows specification of minimum and maximum cardinalities.c. Various data types are supported
Which of the following statements is not correct about XPath?a. It is a simple, declarative language.b. It considers an XML document as a set of XML elements.c. It uses path expressions to refer
Discuss how XML can be used for information exchange.
In the case that an application needs to process large XML documents in a sequential way, it is recommended to use the…a. DOM API.b. SAX API.
Represent the purchase order XML document of Question 1 in JSON and YAML. Contrast the three representations against each other.Question 1Consider our purchase order administration example from
A key difference between XML data and relational data is that…a. Relational data assume atomic data types, whereas XML data can consist of aggregated types.b. Relational data are ordered, whereas
Consider the following table, which maps an XML document to a relational database:Which statement is correct?a. The above table assumes the presence of a DTD or XSD before the mapping can take
Consider the most recent (O)RDBMS products provided by Oracle, IBM, and Microsoft. Discuss and contrast their support in terms of:• Storing XML documents (document-oriented approach, data-oriented
What statement about SQL/XML is not correct?a. It introduces a new XML data type.b. It includes facilities for mapping relational data to XML.c. It includes rules for shredding XML data into
What statement about XQuery is not correct?a. It allows making use of both the document structure and its content.b. It does not allow joining information from different XML documents.c. It uses
In an enterprise application integration (EAI) context, asynchronous communication between objects and/or applications can be achieved by means of…a. Remote procedure call
Which of the following statements is not correct?a. An RDF data model consists of statements which are in subject–predicate–object format.b. RDF allows use of database-specific primary keys to
Which of the following are properties of SPARQL?a. It is based upon matching graph patterns.b. It can query RDF graphs.c. It provides support for namespaces.d. All of the above.
A key benefit of REST when compared to SOAP for web services is that…a. REST has an official standard.b. REST only allows XML for exchanging requests and responses.c. REST is communication
When compared against XML, both JSON and YAML are…a. Not human readable.b. Unable to provide support for ordered elements such as arrays.c. Less technically mature.d. Much more verbose.
Which of the following statements describes NoSQL databases best?a. A NoSQL database offers no support for SQL.b. NoSQL databases do not support joins.c. NoSQL databases are
Write map and reduce functions to perform an aggregation with a MAX function, instead of the AVG and SUM examples we have discussed in this chapter.
Assume you have a list of people and people they are following on Twitter:Write a map–reduce pipeline that outputs a list of commonly followed people per pair of people. E.g.: (Wilfried, Seppe)
Which of the following is not an example of a NoSQL database?a. Graph-based databases.b. XML-based databases.c. Document-based databases.d. All three can be regarded as NoSQL databases.
Which of the following is not a property of a good hash function for use in key–value-based storage structures?a. A hash function should always return the same output for the same input.b. A hash
Using the Neo4j book club database in this chapter, can you do the following using Cypher queries?• Find a list of books no-one likes.• Find all pairs of people that have no liked books in
Which of the following is correct?a. The fact that most NoSQL databases adopt an eventual consistency approach is due to the CAP theorem, which states that strong consistency cannot be obtained when
Which of the following is correct?a. Document stores require users to define document schemas before data can be inserted.b. Document stores require that you perform all filtering and aggregation
What does the following Cypher query express?a. Return all of Bart’s friends, and their friends as well.b. Do not return Bart’s friends, but return their friends.c. Do not return Bart’s
What does DASD stand for?a. Database appropriate storage device.b. Directly accumulative storage device.c. Directly accessible storage device.d. Data accumulative storage device.
What is the I/O boundary? Where are databases situated with regards to this boundary?
When translating a logical data model into an internal data model, what should be taken into account?a. The physical storage properties.b. The types of operations that will be executed on the
What is the expected time for a sequential block access and the expected time for a random block access given a hard disk drive with the following characteristics?• Average seek time = 7.5
How is a row/tuple translated into an internal data model?a. Data item.b. Stored record.c. Dataset.d. Physical storage structure.
If a food delivery service wants to gather the personal information of new clients and uses an online form in which all fields are required to be filled in, which record organization technique would

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