Chapter 13 Designing Databases

18.What is the difference between a primary key and an object identifier?

A primary key identifies one record for a given table. An object identifier identifies one record in the entire database, regardless of the table on which the record exists.

27.Describe the four anomalies that may occur when creating database tables. The four anomalies are:

A. A data redundancy anomaly that occurs when the same data are stored in more than one place in the database. B. An insert anomaly is when the entire primary key is not known and the database cannot insert a new record. C. A deletion anomaly that happens when a record is deleted, resulting in the loss of other related data. D. An update anomaly occurs when a change to one attribute value either causes the database to contain inconsistent data or causes multiple records to need changing.

28.List the eight steps for retrieving, presorting, and presenting data. The eight steps for retrieving and presenting data are:

A. Choose a relation from the database. B. Join two relations together. C. Project columns from the relation. D. Select rows from the relation. E. Derive new attributes. F. Index or sort rows. G. Calculate totals and performance measures. H. Present data.

15.What are the advantages of organizing data storage using a database approach? The advantages of database for data storage are:

A. Data needs to be stored only once for several applications. This implies cost efficiency in terms of storage space and maintenance. B. High data integrity. C. The data have a better chance of being available in a database than in a conventional file system. D. More flexible than separate files. E. Allow users their own view of data./ 16.What are the effectiveness measures of database design? The major effectiveness measures of database design:/ A. Ensure that data can be shared among users for a variety of applications. B. Maintain data that are both accurate and consistent. C. Ensure all data required for current and future applications will be readily available. D. Allow the database to evolve and the needs of the user to grow. E. Allow users to construct their personal view of the data without concern for the way the data are physically stored.

26.List the three entity constraints. In a sentence, describe the meaning of each entity constraint. The three integrity constraints are:

A. Entity integrity constraints, which govern the composition of primary keys. B. Referential integrity, which governs the nature of records in a one-to-many relationship. C. Domain integrity, which defines rules that ensure that only valid data is stored on database records.

31.Explain the differences between traditional databases and data warehouses. Data warehouses are used to organize information for quick and effective queries. The differences between data warehouses and traditional databases are:

A. In the data warehouse, data is organized around major subjects. B. Data in the warehouse is stored as summarized rather than detailed raw data. C. Data in the data warehouse cover a much longer time frame than in a traditional transaction-oriented database. D. Data warehouses are organized for fast queries. E. Data warehouses are usually optimized for answering complex queries, known as OLAP. F. Data warehouses allow for easy access via data-mining software called siftware. G. Data warehouses include multiple databases that have been processed so that data is uniformly defined, containing what is referred to as "clean" data. H. Data warehouses usually contain data from outside sources.

23.What is removed when a relation is converted to the first normal form?

All repeating groups are removed and the primary keys are identified when a relation is converted to the first normal form.

24.What is removed when a relation is converted from 1NF to 2NF?

All the partially dependent attributes are removed and placed in another relation when a relation is converted from 1NF to 2NF.

17.List some examples of entities and their attributes.

Any object or event about which someone chooses to collect data is an entity; for example, a salesperson, a city, or a product.

25.What is removed when a relation is converted from 2NF to 3NF?

Any transitive dependencies, nonkey attributes dependent on other nonkey attributes, are removed when a relation is converted from 2NF to 3NF.

34.What is big data?

Big data is when data sets become too large or too complex to be handled with traditional tools or within traditional databases or data warehouses.

35.Define business analytics.

Business analytics uses quantitative tools to analyze big data and inform decisions of managers and computer systems.

14.What are the advantages of organizing data storage as separate files?

By using files for data storage, systems analysts may expect such advantages as rapid design and building, minimized concerns for data availability and security.

32.What is data mining?

Data mining can identify patterns that a human is unable to detect by using algorithms to search data warehouses for patterns that include associations, sequences, clustering, and trends.

30.Define denormalization.

Denormalization is the process of taking the logical data model and transforming it into an efficient physical model.

19.Define the term "metadata." What is the purpose of metadata?

Metadata is the information that describes data in the file or database. This is used to help users understand the form and structure of the data by providing necessary information about the data itself.

22.Define the term "normalization."

Normalization is the transformation of complex user views and data to a set of smaller, stable data structures.

36.What is text analytics?

Text analytics is a way to structure the unstructured, turning qualitative material into quantitative material. It is used to tap into qualitative unstructured data that can be of use to decision makers who must recommend courses of action to their organizations that are backed by data.

33.What features compose business intelligence (BI)?

The features that compose business intelligence are gathering and storing data, and using knowledge management approaches combined with analysis.

29.What does join do? What is projection? What is selection?

The operation join is intended to take two relations and put them together to make a larger relation. In order for two relations to be joined, they must have a common attribute. Next, projection is the process of building a smaller relation by choosing only relevant attributes from an existing relation. Finally, selection is similar to projection, but instead of extracting columns it extracts rows. Selection creates a new (smaller) relation by extracting records that contain an attribute meeting a certain condition.

37.What are the sources of big data for text analytics?

The sources of big data for text analytics are unstructured qualitative, or "soft," data generated through blogs, chat rooms, questionnaires using open-ended questions, online discussions conducted on the Web, and exchanges occurring on social media such as Facebook, Twitter, and other Web-generated dialogs between customers and an organization.

20.List types of commonly used conventional files. Which of these are temporary files?

The types of commonly used conventional files are: master files, table files, transaction files, work files, and report files. Among these files, master files and table files are permanent, and the rest are temporary files.

21.Name the three main types of database organization.

They are hierarchical database structure, network database structure, and relational database structure.