Module 3 challenge :Process Data from Dirty to Clean (Google Data Analytics Professional Certificate) Answers 2025

Question 1

After a merger, the analyst must handle millions of rows of data efficiently.

✅ SQL
❌ Spreadsheet
❌ Word processor
❌ CSV

Explanation:
SQL (Structured Query Language) is the best tool for managing and analyzing large-scale datasets efficiently. Spreadsheets struggle with performance beyond a few hundred thousand rows.

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Question 2

Convert a float column to integers in SQL:

✅ CAST
❌ SUBSTR
❌ LENGTH
❌ TRIM

Explanation:
The CAST() function converts data from one type to another. Example:

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Question 3

Add a new row of data to a database table:

✅ INSERT INTO
❌ UPDATE
❌ CREATE TABLE IF NOT EXISTS
❌ DROP TABLE IF EXISTS

Explanation:
INSERT INTO adds new data records to a table.
Example:

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Question 4

Retrieve the first 2 characters of each product name and call it product_ID:

✅ SUBSTR(product_name, 1, 2) AS product_ID
❌ SUBSTR AS (1, 2 product_name) product_ID
❌ SUBSTR(product_name) AS (1, 2) product_ID
❌ SUBSTR(product_name, 2) AS product_ID

Explanation:
The SUBSTR() function extracts part of a string.
Syntax: SUBSTR(column_name, start_position, length)
Here: starts at position 1, gets 2 characters.

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Question 5

Remove trailing spaces from data:

✅ TRIM
❌ FORMAT
❌ AVG
❌ SUBSTR

Explanation:
TRIM() removes leading and trailing spaces from text strings:

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Question 6

Return unique computer models without duplicates:

✅ DISTINCT computer_model
❌ DROP computer_model
❌ DUPLICATE computer_model
❌ DELETE computer_model

Explanation:
The DISTINCT clause returns only unique values.
Example:

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Question 7

Tidy up a database cluttered with irrelevant tables:

✅ DROP TABLE IF EXISTS
❌ INSERT INTO
❌ UPDATE
❌ CREATE TABLE IF NOT EXISTS

Explanation:
DROP TABLE IF EXISTS deletes a table only if it already exists — helpful for cleanup operations.

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Question 8

Check for credit card numbers longer than 16 characters:

✅ LENGTH(credit_card_numbers) > 16
❌ COUNT(credit_card_numbers) > 16
❌ WHERE(credit_card_numbers) < 16
❌ IDENTIFY(credit_card_numbers) < 16

Explanation:
The LENGTH() function counts the number of characters in a string.
Combine with a condition to detect anomalies:

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Question 9

Replace null values in a column with a different column’s value:

✅ COALESCE
❌ TRIM
❌ CONCAT
❌ CAST

Explanation:
COALESCE() returns the first non-null value in a list:

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🧾 Summary Table

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