Question 1

When a table is created using existing data from multiple sources,you are likely to find that some data values have never been provided because the values are not known.This is an example of ________.

Accepted Answer

The missing values problem occurs when some data values are not provided because they are not known. This can happen when creating a table from multiple sources of data, where some sources may not have provided certain values. The multivalued, multicolumn problem refers to situations where a single piece of data can have multiple values or when a single entity has multiple attributes that can change over time. The inconsistent values problem refers to situations where the same data has been represented in multiple ways or where data values conflict with each other. The general-purpose remarks column problem occurs when a table has a column that is used to provide general comments or remarks, but the data in the column is unorganized and inconsistent.

Question 2

Explain denormalization,and why it may be appropriate to denormalize a set of tables.

Accepted Answer

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Question 3

A missing value is called a(n)________.

Accepted Answer

A null value is a term commonly used in databases and programming to represent a missing or unknown value. It indicates that the data is absent or not applicable, rather than being a zero or blank space.

Question 4

The SQL keyword IS NULL can be used to help ________.

Accepted Answer

The SQL keyword IS NULL is used to check if a value in a column is null or not. Therefore, it can be used to count the number of null values in a column. It cannot be used to count the number of columns or rows in a table.

Question 5

Reviewing the work done on a table that was created using existing data from multiple sources,you find that a column named Remarks has been included,and it is populated with inconsistent and verbose verbal data.This is an example of ________.

Accepted Answer

The presence of an inconsistent and verbose verbal data in a column named Remarks indicates that a general-purpose remarks column problem exists. This problem arises when a column is created to accommodate any data that does not fit into existing columns, resulting in a verbose and inconsistent column.

Question 6

When a table is created using existing data,you are likely to find that some data values have never been provided because any value there would be inappropriate.This is an example of ________.

Accepted Answer

This scenario describes the missing values problem, where there are missing data values that were not provided due to their inappropriate nature. The multivalued, multicolumn problem refers to a situation where a table has multiple values in one column or multiple columns have similar values. The inconsistent values problem refers to situations where there are conflicting data values. The general-purpose remarks column problem is when a table has a column for general comments instead of specific data columns.

Question 7

To check for null values in a column in a table,use the SQL phrase ________.

Accepted Answer

The SQL phrase "IS NULL" is used to check if a column in a table contains null values. The other options are not relevant for this purpose.

Question 8

When accessing table structure,and determining the number and types of columns in a table,how can you control how many rows are returned?

Accepted Answer

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Question 9

What are null values,and why are they a problem?

Accepted Answer

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Question 10

What is the multivalue,multicolumn problem,and why is it a problem? Include an example.

Accepted Answer

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Question 11

When accessing table structure,how do you determine how many rows are in a table?

Accepted Answer

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Question 12

You are creating a PRODUCT table using existing data from multiple sources.Examining the data,you find that you have "large red hat","large hat,red","red hat large" and "hat,large,red." This is an example of ________.

Accepted Answer

The issue described is known as the inconsistent values problem, which refers to the challenge of dealing with data that has different formats or values for the same piece of information. While options A, C, and D are also common data management issues, they do not describe the situation presented in this question.

Question 13

A null value can indicate which of the following conditions?

Accepted Answer

A null value indicates that the value is not available or has not been provided. It does not indicate whether the value is correct or incorrect, updated or unchangeable. A null value can indicate that the value is appropriate but unknown, which is why option B is the correct answer.

Question 14

The problem of misspelled data entries is really the same as ________.

Accepted Answer

Misspelled data entries can lead to inconsistent values problem, where the same entity may have different values due to different spellings or variations in spelling. For example, "Color" and "Colour" are different spellings of the same word and can lead to inconsistency in the dataset. The other options are not directly related to misspelled data entries.

Question 15

What are the advantages and disadvantages of normalization?

Accepted Answer

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Question 16

Reviewing the work done on a table that was created using existing data from multiple sources,you are likely to find that some data values that were provided were never entered into the table.This is an example of ________.

Accepted Answer

The situation described is known as the missing values problem, which refers to the absence of data values that should have been included in a table or database. The other options (multivalued/multicolumn problem, inconsistent values problem, and general-purpose remarks column problem) refer to different issues that may arise when working with data but are not relevant to the scenario described.

Question 17

When assessing table structure,how do you determine the number and types of columns in a table?

Accepted Answer

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Question 18

Describe the steps in assessing table structure when you are given a set of tables and asked to construct a new database to store the existing data.

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Question 19

What are general-purpose remarks columns,and why are they a problem?

Accepted Answer

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Question 20

What are inconsistent values,and why are they a problem?

Accepted Answer

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Quiz 4: Database Design Using Normalization