SQL for Analysts — Quiz | Data Analytics using Python

Question 1

Which clause filters individual rows BEFORE grouping?

A HAVING

B WHERE

C ORDER BY

D GROUP BY

Question 2

Which clause filters groups AFTER aggregation (e.g. SUM() > 3000)?

A WHERE

B HAVING

C SELECT

D LIMIT

Question 3

A LEFT JOIN returns…

A only matching rows

B all rows from the left table plus any matches from the right

C all rows from the right table

D every combination

Question 4

An INNER JOIN returns…

A all rows from both tables

B only rows that match in both tables

C the left table only

D no rows

Question 5

What is a CTE?

A A type of index

B A named temporary result defined with WITH

C A chart

D A database backup

Question 6

Window functions differ from GROUP BY because they…

A are slower always

B compute across related rows WITHOUT collapsing them

C only work on text

D cannot rank

Question 7

Which window function gives the previous row's value (for % change)?

A ROW_NUMBER()

B LAG()

C NTILE()

D RANK()

Question 8

In RANK() OVER (PARTITION BY region ORDER BY revenue DESC), PARTITION BY sets…

A the sort order

B the group within which ranking restarts

C the table name

D the column to return

Question 9

Which adds if/then logic inside a query?

A IF FILE

B CASE WHEN ... THEN ... END

C SWITCH

D WHEN ONLY

Question 10

Which replaces NULLs with a default value?

A ISNULL_ONLY()

B COALESCE(col, 0)

C DROP NULL

D NVL_NONE()

Question 11

A good optimisation habit is to…

A always use SELECT *

B select only needed columns and filter early

C avoid indexes

D pull all rows into Python first

Question 12

Which brings a SQL query result directly into a Pandas DataFrame?

A pd.sql()

B pd.read_sql(query, engine)

C engine.to_pandas()

D sql.fetch()