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What does the ROW_NUMBER() function do in SQL?

easy📝 Conceptual Q11 of 15
SQL - Window Functions Fundamentals
What does the ROW_NUMBER() function do in SQL?
ACounts the total number of rows in a table.
BFilters rows based on a condition.
CCalculates the sum of values in a column.
DAssigns a unique sequential number to each row in the result set.
Step-by-Step Solution
Solution:

  1. Step 1: Understand the purpose of ROW_NUMBER()

    The ROW_NUMBER() function assigns a unique sequential integer to rows in the result set, starting at 1.

  2. Step 2: Compare with other options

    Counting rows, summing values, or filtering rows are done by other SQL functions like COUNT(), SUM(), or WHERE clause, not ROW_NUMBER().

  3. Final Answer:

    Assigns a unique sequential number to each row in the result set. -> Option D

  4. Quick Check:

    ROW_NUMBER() = unique row numbers [OK]
Quick Trick: ROW_NUMBER() gives each row a unique number starting at 1 [OK]
Common Mistakes:
  • Confusing ROW_NUMBER() with COUNT()
  • Thinking ROW_NUMBER() filters rows
  • Assuming ROW_NUMBER() sums values

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