[Solved] Why is it important to include an ELSE clause when using CASE in a WHERE clause? — Ans: To handle all possible cases and avoid NULL results that cause unexpected... | SQL

SQL - CASE Expressions

Why is it important to include an ELSE clause when using CASE in a WHERE clause?

ATo improve query performance by indexing

BTo handle all possible cases and avoid NULL results that cause unexpected filtering

CTo create new columns in the output

DTo allow CASE to be used in GROUP BY clauses

Step-by-Step Solution

Solution:

Step 1: Understand CASE behavior without ELSE
If ELSE is missing, CASE returns NULL for unmatched conditions.
Step 2: Effect on WHERE filtering
NULL in WHERE condition causes rows to be excluded unexpectedly.
Final Answer:
To handle all possible cases and avoid NULL results that cause unexpected filtering -> Option B
Quick Check:
ELSE prevents NULL filtering issues in CASE [OK]

Quick Trick: Always include ELSE to avoid NULL in CASE [OK]

Common Mistakes:

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Why is it important to include an ELSE clause when using CASE in a WHERE clause?