Why does PostgreSQL require explicit column definitions in RETURNS TABLE functions instead of inferring them automatically?

hard📝 Conceptual Q10 of 15

PostgreSQL - Advanced PL/pgSQL

Why does PostgreSQL require explicit column definitions in RETURNS TABLE functions instead of inferring them automatically?

ABecause RETURNS TABLE functions cannot return NULL values

BBecause PostgreSQL cannot execute queries inside functions

CTo prevent functions from returning multiple rows

DTo ensure the function's output structure is clear and consistent

Step-by-Step Solution

Solution:

Step 1: Understand the purpose of explicit column definitions
Explicit column definitions make the output structure clear, helping clients and tools know what to expect.
Step 2: Evaluate incorrect options
PostgreSQL can execute queries inside functions, functions can return multiple rows, and NULL values are allowed.
Final Answer:
To ensure the function's output structure is clear and consistent -> Option D
Quick Check:
Explicit columns clarify output structure = A [OK]

Quick Trick: Explicit columns define clear output structure for RETURNS TABLE [OK]

Common Mistakes:

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