[Solved] What happens when you use GROUP BY on a column that contains NULL values in SQL? — Ans: All rows with NULL in that column are grouped together as one group. | SQL

SQL - GROUP BY and HAVING

What happens when you use GROUP BY on a column that contains NULL values in SQL?

AEach NULL value is treated as a unique group.

BAll rows with NULL in that column are grouped together as one group.

CRows with NULL values are ignored in the grouping.

DThe query will return an error due to NULL values.

Step-by-Step Solution

Solution:

Step 1: Understand GROUP BY behavior with NULLs
In SQL, NULL values are considered equal for grouping purposes, so all NULLs form one group.
Step 2: Confirm grouping of NULL values
When grouping, rows with NULL in the grouped column are combined into a single group labeled as NULL.
Final Answer:
All rows with NULL in that column are grouped together as one group. -> Option B
Quick Check:
GROUP BY NULL values = single group [OK]

Quick Trick: NULLs group together as one group in GROUP BY [OK]

Common Mistakes:

MISTAKES

Master "GROUP BY and HAVING" in SQL

9 interactive learning modes - each teaches the same concept differently

More SQL Quizzes

What happens when you use GROUP BY on a column that contains NULL values in SQL?