Module 3: Database essentials

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In this post, I provide accurate answers and detailed explanations for Module 3: Database essentials of Course 3: Prepare Data for Exploration – Google Data Analytics Professional Certificate.

Whether you’re preparing for quizzes or brushing up on your knowledge, these insights will help you master the concepts effectively. Let’s dive into the correct answers and detailed explanations for each question.

Test your knowledge on working with databases

Practice Quiz

1. Fill in the blank: A _____ is an identifier that references a database column in which each value is unique.

  • relation
  • field
  • foreign key
  • primary key ✅

Explanation:
A primary key uniquely identifies each record in a database table. It ensures that no two rows have the same key value, allowing for precise data referencing.

2. Fill in the blank: A relational database contains a series of _____ that can be connected to form relationships.

  • fields
  • cells
  • spreadsheets
  • tables ✅

Explanation:
In a relational database, data is organized into tables, and these tables are related to each other using keys (primary and foreign). This structure enables efficient data organization and querying.

3. A key benefit of working with normalized databases is that they help lower data redundancy. Which of the following is an example of redundancy?

  • A database containing two foreign keys
  • A database that forms two or more relationships
  • The same piece of data being stored in two different places ✅
  • Team members in different office locations working with the same data

Explanation:
Redundancy occurs when identical data is stored in multiple locations within a database. This can lead to inconsistencies and increased storage requirements, which normalization aims to prevent.

Test your knowledge on metadata

Practice Quiz

4. A large company has several data collections across its many departments. What kind of metadata indicates exactly how many collections a piece of data lives in?

  • Structural ✅
  • Administrative
  • Descriptive
  • Representative

Explanation:
Structural metadata provides information about how data is organized and stored, such as the number of collections it exists in, its format, and its relationships with other data.

5. The date and time a photo was taken is an example of which kind of metadata?

  • Descriptive
  • Structural
  • Representative
  • Administrative ✅

Explanation:
Administrative metadata includes information about the creation, management, and preservation of data, such as the date and time a photo was taken or its file type.

6. A large metropolitan high school gives each of its students an ID number to differentiate them in its database. What kind of metadata are the ID numbers?

  • Descriptive ✅
  • Administrative
  • Representative
  • Structural

Explanation:
Descriptive metadata is used to describe or identify data. In this case, the student ID numbers serve as identifiers, making them a type of descriptive metadata.

7. A company needs to merge third-party data with its own data. Which of the following actions will help make this process successful? Select all that apply.

  • Use the metadata to evaluate the third-party data’s quality and credibility. ✅
  • Use the metadata to standardize the data. ✅
  • Alter the company’s metadata to more closely reflect the incoming metadata.
  • Replace the incoming data’s metadata with its own company metadata.

Explanation:

  • Metadata can provide insights into the quality, source, and credibility of third-party data, which is crucial before integration.
  • Standardizing metadata ensures consistency and compatibility between the company’s data and the third-party data.
  • Altering or replacing metadata without careful consideration can lead to loss of important context and decrease data reliability.

Test your knowledge on accessing data sources

Practice Quiz

8. A CSV file saves data in a table format. What does CSV stand for?

  • Comma-separated values ✅
  • Compatible scientific variables
  • Cell-structured variables
  • Calculated spreadsheet values

Explanation:
CSV stands for comma-separated values, a file format where data is saved in plain text, with values separated by commas to represent a table structure.

9. A data analyst wants to bring data from a CSV file into a spreadsheet. This is an example of what process?

  • Normalizing data
  • Filing data
  • Importing data ✅
  • Editing data

Explanation:
Importing data involves transferring data from one format or file (like a CSV file) into another, such as a spreadsheet.

10. A CSV file makes it easier for data analysts to complete which tasks? Select all that apply.

  • Manage multiple tabs within a worksheet
  • Import data to a new spreadsheet ✅
  • Distinguish values from one another ✅
  • Examine a small subset of a large dataset ✅

Explanation:

  • Import data to a new spreadsheet: CSV files are widely compatible and can be easily imported into spreadsheet software.
  • Distinguish values from one another: Commas in a CSV file separate data into distinct fields, making it easy to identify individual values.
  • Examine a small subset of a large dataset: Analysts can save or extract smaller, manageable portions of a large dataset in CSV format for focused analysis.

Note: CSV files do not support managing multiple tabs within a worksheet, as they are limited to single-sheet data.

Test your knowledge on sorting and filtering

Practice Quiz

11. What is the process for arranging data into a meaningful order to make it easier to understand, analyze, and visualize?

  • Filtering
  • Prioritizing
  • Reframing
  • Sorting ✅

Explanation:
Sorting organizes data in a specific order, such as ascending or descending, to make patterns and trends more evident for analysis and visualization.

12. A data analyst is reviewing a national database of real estate sales. They are only interested in sales of condominiums. How can the analyst narrow their scope?

  • Sort by condominium sales
  • Sort by non-condominium sales
  • Filter out condominium sales
  • Filter out non-condominium sales ✅

Explanation:
Filtering out non-condominium sales removes unnecessary data, leaving only the records of interest, i.e., condominium sales.

13. A data analyst works for a rental car company. They have a spreadsheet that lists car ID numbers and the dates cars were returned. How can they sort the spreadsheet to find the most recently returned cars?

  • By return date, in descending order ✅
  • By car numerical ID, in descending order
  • By return date, in ascending order
  • By car numerical ID, in ascending order

Explanation:
Sorting by return date in descending order places the most recent dates at the top of the list, making it easy to identify the latest returned cars.

14. Fill in the blank: To keep a header row at the top of a spreadsheet, highlight the row and select _____ from the View menu.

  • Pin
  • Freeze ✅
  • Lock
  • Set

Explanation:
The Freeze option allows you to lock the header row at the top of the spreadsheet, so it remains visible while scrolling through the data.

Test your knowledge on using SQL with large datasets

Practice Quiz

15. In MySQL, what is acceptable syntax for the SELECT keyword? Select all that apply.

  • select ✅
  • ‘SELECT’
  • SELECT ✅
  • “SELECT”

Explanation:
In MySQL, the SELECT keyword is case-insensitive, so both SELECT and select are valid. However, enclosing SELECT in single (”) or double (“”) quotes turns it into a string literal, which causes an error. Therefore, SELECT and select (without quotes) are the correct syntaxes.

16. Which cases are most often used for column names in a database table, and represent a best practice? Select all that apply.

  • Sentence case
  • Lower case ✅
  • Camel case ✅
  • Snake case ✅

Explanation:
 Lowercase, camel case (e.g., columnName), and snake case (e.g., column_name) are commonly used for column names in database tables. These cases enhance consistency and readability. Sentence case is not a common practice for column naming.

17. In BigQuery, what optional syntax can be removed from the following FROM clause without stopping the query from running?

FROM `bigquery-public-data.sunroof_solar.solar_potential_by_postal_code`

  • Dashes
  • Backticks ✅
  • Dots
  • Underscores

Explanation:
 In BigQuery, backticks are optional unless there are special characters, spaces, or reserved words in the table name. Removing backticks in this example does not stop the query from running.

18. In the following FROM clause, what is the table name in the SQL query?

FROM bigquery-public-data.sunroof_solar.solar_potential_by_postal_code

  • sunroof_solar
  • solar_potential_by_postal_code ✅
  • solar.solar
  • public-data.sunroof

Explanation: The full structure represents the project, dataset, and table. Here:

  • bigquery-public-data is the project name.
  • sunroof_solar is the dataset name.
  • solar_potential_by_postal_code is the table name.

*Module 3 challenge*

Graded Quiz.

19. Primary and foreign keys are two connected identifiers within separate tables. These tables exist in what kind of database?

  • Metadata
  • Primary
  • Relational ✅
  • Normalized

20. When working with data from an external source, what can metadata help data analysts do? Select all that apply.

  • Ensure data is clean and reliable ✅
  • Combine data from more than one source ✅
  • Understand the  contents of a database ✅
  • Choose which analyses to run

21.Think about data as a student at a high school. In this metaphor, which of the following are examples of metadata? Select all that apply.

  • Student’s ID number ✅
  • Student’s enrollment date ✅
  • Classes the student is enrolled in ✅
  • Grades the student earns

22. Fill in the blank: Data _____ is the process of ensuring the formal management of a company’s data assets.

  • aggregation
  • integrity
  • mapping
  • governance ✅

Explanation:
Data governance refers to the formal management process of ensuring data integrity, privacy, security, and accessibility within an organization.

23. In what circumstance might a data analyst choose not to use external data in their analysis?

  • The data represents diverse perspectives
  • The data is too thorough
  • The data is free for anyone to access
  • The data cannot be confirmed to be reliable ✅

Explanation:
 If external data is not reliable or cannot be validated, a data analyst may choose not to use it to avoid errors or misleading insights.

24. A nonprofit maintains a list of how many laptops they provide to each school in the county. In the table, there is a column called number_of_laptops. A data analyst wants to determine which schools were given the fewest laptops. How should they sort the data to return these schools first?

  • Sort alphabetically in ascending order
  • Sort numerically in descending order
  • Sort alphabetically in descending order
  • Sort numerically in ascending order ✅

25. When writing a query, it's necessary for the name of the dataset to be inside two backticks in order for the query to run properly.

  • True
  • False ✅

26. You are working with a database table that contains customer data. The city column lists the city where each customer is located. You want to find out which customers are located in Berlin.

You write the SQL query below. Add a WHERE clause that will return only customers located in Berlin.

How many customers are located in Berlin?

  • 9
  • 12
  • 2 ✅
  • 7

27. Relational databases contain a series of tables connected to form relationships. Which two types of fields exist in two connected tables?

  • Star and snowflake schemas
  • Descriptive and structural metadata
  • Internal and external data
  • Primary and foreign keys ✅

28. Data analysts use metadata for what tasks? Select all that apply.

  • To combine data from more than one source ✅
  • To perform data analyses
  • To interpret the contents of a database ✅
  • To evaluate the quality of data ✅

Explanation:
Metadata provides information about the structure, content, and quality of data, allowing data analysts to interpret, combine, and evaluate it from various sources.

29. Think about data as driving a taxi cab. In this metaphor, which of the following are examples of metadata? Select all that apply.

  • Company that owns the taxi ✅
  • License plate number ✅
  • Make and model of the taxi cab ✅
  • Passengers the taxi picks up

30. Fill in the blank: Data governance is the process of ensuring that a company’s _____ are managed in a formal manner.

  • business tasks
  • data engineers
  • data assets ✅
  • business strategies

31. What are some key benefits of using external data? Select all that apply.

  • External data is always reliable.
  • External data is free to use.
  • External data has broad reach. ✅
  • External data can provide industry-level perspectives. ✅

32. A data analyst reviews a national database of movie theater showings. They want to find the first movies shown in San Francisco in 2001. How can they organize the data to return the first 10 movies shown at the top of their list? Select all that apply.

  • Filter out showings not in 2001 ✅
  • Sort by date in descending order
  • Sort by date in ascending order ✅
  • Filter out showings outside of San Francisco ✅

33. You are working with a database table that contains customer data. The state column lists the state where each customer is located. The state names are abbreviated. You want to find out which customers are located in the state of Florida (FL).

You write the SQL query below. Add a WHERE clause that will return only customers located in FL.

How many customers are located in FL?

  • 6
  • 4
  • 1 ✅
  • 3

Explanation:
The SQL query SELECT * FROM customer WHERE state = 'FL' will return only the customers located in Florida. The output will show that there is 1 customer in FL.

34. Structural metadata indicates how a piece of data is organized and whether it’s part of one or more than one data collection.

  • True ✅
  • False

Explanation:
Structural metadata describes the organization of data, such as its format, relationships, and whether it belongs to one or multiple collections.

35. Relational databases illustrate relationships between tables. Which fields represent the connection between these tables? Select all that apply.

  • Foreign keys ✅
  • External keys
  • Primary keys ✅
  • Secondary keys

Explanation:
 In relational databases, primary keys uniquely identify each record in a table, and foreign keys establish a link between two tables by referencing the primary key of another table.

36. When writing a query, you must remove the two backticks around the name of the dataset in order for the query to run properly.

  • True
  • False ✅

Explanation:
In SQL, backticks are used to enclose dataset or column names, especially when they are reserved keywords or contain spaces. They are necessary in some cases, so removing them would cause an error.

37. You are working with a database table that contains customer data. The first_name column lists the first name of each customer. You are only interested in customers with the first name Mark.

You write the SQL query below. Add a WHERE clause that will return only customers named Mark.

How many customers are named Mark?

  • 1
  • 5
  • 3
  • 2 ✅

38. Metadata is data about data. What kinds of information can metadata offer about a particular dataset? Select all that apply.

  • How to combine the data with another dataset ✅
  • Which analyses to perform on the data
  • If the data is clean and reliable ✅
  • What kinds of data it contains ✅

39. A data analyst reviews a database of Wisconsin car sales to find the last car models sold in Milwaukee in 2019. How can they sort and filter the data to return the last five cars sold at the top of their list? Select all that apply.

  • Filter out sales outside of Milwaukee ✅
  • Filter out sales not in 2019 ✅
  • Sort by sale date in descending order ✅
  • Sort by sale date in ascending order

Explanation:
 The analyst can filter by location (Milwaukee) and time (2019), and sort by the sale date in descending order to return the most recent sales.

40. When writing a query, the name of the dataset can either be inside two backticks, or not, and the query will still run properly.

  • True ✅
  • False

41. A data analyst chooses not to use external data because it represents diverse perspectives. This is an appropriate decision when working with external data.

  • True
  • False ✅

Related contents:

Module 1: Data types and structures
Module 2: Data responsibility
Module 4: Organize and protect data
Module 6: *Course challenge*​

You might also like:

Course 1: Foundations: Data, Data, Everywhere
Course 2: Ask Questions to Make Data-Driven Decisions
Course 4: Process Data from Dirty to Clean
Course 5: Analyze Data to Answer Questions
Course 6: Share Data Through the Art of Visualization
Course 7: Data Analysis with R Programming
Course 8: Google Data Analytics Capstone: Complete a Case Study

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