A data analyst receives a request for the current employee head count and runs the following SQL statement:
SELECT COUNT(EMPLOYEE_ID) FROM JOBS
The returned head count is higher than expected because employees can have multiple jobs. Which of the following should return an accurate employee head count?
Correct Answer:
D
This question falls under theData Analysisdomain of CompTIA Data+ DA0-002, which involves using SQL queries to analyze data and address issues like duplicates in datasets. The issue here is that the initial query counts all instances of EMPLOYEE_ID in the JOBS table, but employees can have multiple jobs, leading to an inflated head count. The goal is to count unique employees.
✑ SELECT JOB_TYPE, COUNT DISTINCT(EMPLOYEE_ID) FROM JOBS (Option
A): This query is syntactically incorrect because COUNT DISTINCT(EMPLOYEE_ID) should use parentheses as COUNT(DISTINCT EMPLOYEE_ID). It also groups by JOB_TYPE, which is unnecessary for a total head count.
✑ SELECT DISTINCT COUNT(EMPLOYEE_ID) FROM JOBS (Option B): This query
is incorrect because DISTINCT applies to the rows returned, not the COUNT function directly. It doesn??t address the duplicate EMPLOYEE_ID issue.
✑ SELECT JOB_TYPE, COUNT(DISTINCT EMPLOYEE_ID) FROM JOBS (Option
C ): While this query correctly uses COUNT(DISTINCT EMPLOYEE_ID) to count unique employees, grouping by JOB_TYPE breaks the count into separate groups, which isn??t required for a total head count.
✑ SELECT COUNT(DISTINCT EMPLOYEE_ID) FROM JOBS (Option D): This query
correctly counts only unique EMPLOYEE_IDs by using the DISTINCT keyword within the COUNT function, providing an accurate total head count without grouping.
The DA0-002 Data Analysis domain emphasizes "given a scenario, applying the appropriate descriptive statistical methods using SQL queries," which includes handling duplicates with functions like COUNT(DISTINCT). Option D is the most direct and accurate method for a total unique head count.
Reference: CompTIA Data+ DA0-002 Draft Exam Objectives, Domain 3.0 Data Analysis.
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Which of the following data repositories should a company use when structured data about the whole company needs to be stored in a predefined data structure?
Correct Answer:
B
This question pertains to theData Concepts and Environmentsdomain, focusing on selecting the appropriate repository for structured data across an entire company. The requirement for a predefined structure narrows the options.
✑ Data mart (Option A): A data mart stores structured data for a specific business
area (e.g., sales), not the whole company.
✑ Data warehouse (Option B): A data warehouse is designed to store structured data from across the entire company in a predefined schema, optimized for analytics and reporting.
✑ Data silo (Option C): A data silo is an isolated repository, often structured, but not designed for company-wide integration.
✑ Data lake (Option D): A data lake stores raw data (structured and unstructured) without a predefined structure, not suitable for this requirement.
The DA0-002 Data Concepts and Environments domain includes understanding "different types of databases and data repositories," and a data warehouse is ideal for company-wide structured data.
Reference: CompTIA Data+ DA0-002 Draft Exam Objectives, Domain 1.0 Data Concepts and Environments.
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Which of the following best describes an assessment a data analyst would use to validate that the number of records in a dataset matches the expected results?
Correct Answer:
B
This question pertains to theData Governancedomain, focusing on data quality validation techniques. The task is to validate that the number of records matches expectations, which requires a specific type of assessment.
✑ Source control (Option A): Source control (e.g., Git) manages code versions, not dataset validation.
✑ Unit test (Option B): A unit test checks a specific component of a process, such as verifying that the number of records in a dataset matches the expected count, making it the best fit.
✑ Stress test (Option C): Stress tests evaluate system performance under load, not record counts.
✑ Health check (Option D): A health check monitors system status but isn??t specific to validating record counts.
The DA0-002 Data Governance domain includes "data quality control concepts," and unit tests are a standard method for validating specific data outcomes like record counts. Reference: CompTIA Data+ DA0-002 Draft Exam Objectives, Domain 5.0 Data Governance.
Which of the following file types separates data using a delimiter?
Correct Answer:
D
This question falls under theData Concepts and Environmentsdomain, focusing on understanding file formats and their structures. The task is to identify a file type that uses delimiters to separate data.
✑ XML (Option A): XML uses tags to structure data, not delimiters.
✑ HTML (Option B): HTML is a markup language for web pages, not a data file format using delimiters.
✑ JSON (Option C): JSON uses key-value pairs and nested structures, not delimiters like commas.
✑ CSV (Option D): CSV (Comma-Separated Values) uses delimiters (typically commas) to separate data fields, making it the correct choice.
The DA0-002 Data Concepts and Environments domain includes understanding "data schemas and dimensions," such as file formats like CSV that use delimiters.
Reference: CompTIA Data+ DA0-002 Draft Exam Objectives, Domain 1.0 Data Concepts and Environments.
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A data analyst is creating a new dataset that involves bringing together the following datasets:
Name ID
Date of birth
Frank 23525
3/19
Martha 11290
6/13
Ellen 12141
11/4
ID
Address City State 23525
1234 Harding Chicago
IL 11040
935 Terrace Hills Chino
CA 11290
2 Speedway Miami
FL
Which of the following would be the output if the data analyst does a FULL JOIN?
Correct Answer:
D
This question falls under theData Concepts and Environmentsdomain, focusing on database operations like joins. A FULL JOIN combines all rows from both tables, including matches and non-matches, filling in NULLs where there??s no corresponding data.
✑ The first table has IDs: 23525 (Frank), 11290 (Martha), 12141 (Ellen).
✑ The second table has IDs: 23525, 11040, 11290.
✑ A FULL JOIN includes all IDs: 23525, 11290, 12141, 11040.
✑ Option A: Incorrect; it includes a row for Ellen with "2 Speedway," but Ellen??s ID (12141) doesn??t match any address, and 11040 is missing.
✑ Option B: Identical to Option A, so incorrect for the same reasons.
✑ Option C: Incorrect; it mismatches addresses (e.g., Ellen with 935 Terrace Hills, which belongs to 11040).
✑ Option D: Correct; it includes all IDs, with NULLs for non-matching rows (Ellen has no address, and 11040 has no name).
The DA0-002 Data Concepts and Environments domain includes understanding "data schemas and dimensions," such as performing joins in relational databases.
Reference: CompTIA Data+ DA0-002 Draft Exam Objectives, Domain 1.0 Data Concepts and Environments.
==============
