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Which SQL function is commonly used to compare a row with the next row to find gaps in a sequence?

easy📝 Conceptual Q2 of 15
SQL - Advanced Query Patterns
Which SQL function is commonly used to compare a row with the next row to find gaps in a sequence?
ASUM()
BLEAD()
CCOUNT()
DMAX()
Step-by-Step Solution
Solution:

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

    LEAD() lets you look at the next row's value without joining the table to itself.

  2. Step 2: Compare current and next row values

    By comparing current and next values, you can detect if numbers skip, indicating a gap.

  3. Final Answer:

    LEAD() -> Option B

  4. Quick Check:

    Function to peek next row = LEAD() [OK]
Quick Trick: Use LEAD() to peek at next row value [OK]
Common Mistakes:
  • Using COUNT() to find gaps
  • Using aggregate functions incorrectly
  • Not comparing adjacent rows

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