[Solved] What will the following query output given table seq with values (10, 11, 13, 14, 15)?SELECT num + 1 AS gap_start FROM seq WHERE num + 1 LEAD(num) OVER (ORDER BY num); | SQL

SQL - Advanced Query Patterns

What will the following query output given table seq with values (10, 11, 13, 14, 15)?

SELECT num + 1 AS gap_start FROM seq WHERE num + 1 <> LEAD(num) OVER (ORDER BY num);

A12

B11

C14

D15

Step-by-Step Solution

Solution:

Step 1: Identify next values using LEAD()
Values: 10,11,13,14,15; Next: 11,13,14,15,NULL
Step 2: Find where num + 1 differs from next num
10+1=11 equals 11 (no gap); 11+1=12 not equal 13 (gap 12)
Final Answer:
12 -> Option A
Quick Check:
Gap found at 12 [OK]

Quick Trick: Gap is num+1 when it differs from next num [OK]

Common Mistakes:

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