[Solved] Given the table sales with data:product | region -------|-------- A | East B | NULL A | NULL B | East NULL | West NULL | NULL What is the result of:SELECT region, COUNT(*) FROM sales GROUP BY region... | SQL

SQL - GROUP BY and HAVING

Given the table sales with data:

product | region
-------|--------
A      | East
B      | NULL
A      | NULL
B      | East
NULL   | West
NULL   | NULL

What is the result of:

SELECT region, COUNT(*) FROM sales GROUP BY region ORDER BY region;

A[ {"region": "East", "count": 2}, {"region": "NULL", "count": 3}, {"region": "West", "count": 1} ]

B[ {"region": "East", "count": 2}, {"region": "NULL", "count": 2}, {"region": "West", "count": 1} ]

C[ {"region": "East", "count": 2}, {"region": null, "count": 2}, {"region": "West", "count": 1} ]

D[ {"region": null, "count": 3}, {"region": "East", "count": 2}, {"region": "West", "count": 1} ]

Step-by-Step Solution

Solution:

Step 1: Group rows by region including NULLs
Rows with region 'East' = 2, 'West' = 1, and NULL values (3 rows) are grouped together as one NULL group.
Step 2: Understand NULL display and count
SQL returns NULL as null (not string 'NULL'). Count for NULL group is 3 because three rows have region NULL. ORDER BY region ASC places null first.
Final Answer:
[{"region": null, "count": 3}, {"region": "East", "count": 2}, {"region": "West", "count": 1}] -> Option D
Quick Check:
GROUP BY NULL groups count 3, NULL shown as null [OK]

Quick Trick: NULLs group together and show as null, not 'NULL' string [OK]

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