[Solved] Why does NTILE sometimes create groups with different numbers of rows? — Ans: Because the total rows may not divide evenly by the number of groups | SQL

SQL - Window Functions Fundamentals

Why does NTILE sometimes create groups with different numbers of rows?

ABecause the total rows may not divide evenly by the number of groups

BBecause NTILE randomly assigns rows to groups

CBecause NTILE ignores the ORDER BY clause

DBecause NTILE requires a GROUP BY clause

Step-by-Step Solution

Solution:

Step 1: Understand NTILE grouping logic
NTILE divides rows into groups as evenly as possible but leftover rows cause some groups to have one more row.
Step 2: Eliminate incorrect reasons
NTILE does not assign rows randomly, respects ORDER BY, and does not require GROUP BY.
Final Answer:
Because the total rows may not divide evenly by the number of groups -> Option A
Quick Check:
Unequal groups due to leftover rows [OK]

Quick Trick: Unequal groups happen when rows don't divide evenly [OK]

Common Mistakes:

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Why does NTILE sometimes create groups with different numbers of rows?