[Solved] What does the ROW_NUMBER() function do in PostgreSQL? — Ans: Assigns a unique sequential number to each row in the result set. | PostgreSQL

PostgreSQL - Window Functions in PostgreSQL

What does the ROW_NUMBER() function do in PostgreSQL?

ACounts the total number of rows in the table.

BAssigns the same rank to rows with identical values, skipping ranks after ties.

CAssigns ranks to rows without skipping numbers after ties.

DAssigns a unique sequential number to each row in the result set.

Step-by-Step Solution

Solution:

Step 1: Understand ROW_NUMBER() purpose
ROW_NUMBER() gives each row a unique sequential number, starting at 1.
Step 2: Compare with RANK() and DENSE_RANK()
Unlike RANK() or DENSE_RANK(), ROW_NUMBER() never assigns the same number to multiple rows.
Final Answer:
Assigns a unique sequential number to each row in the result set. -> Option D
Quick Check:
ROW_NUMBER() = unique row numbers [OK]

Quick Trick: ROW_NUMBER always gives unique numbers, no ties allowed [OK]

Common Mistakes:

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What does the ROW_NUMBER() function do in PostgreSQL?