[Solved] Identify the error in this query:SELECT * FROM (VALUES (1, 'a'), (2, 'b')) AS t(id, letter, extra); — Ans: Too many column aliases for the number of columns in VALUES | PostgreSQL

PostgreSQL - Set Operations and Advanced Queries

Identify the error in this query:

SELECT * FROM (VALUES (1, 'a'), (2, 'b')) AS t(id, letter, extra);

AToo many column aliases for the number of columns in VALUES

BMissing AS keyword before alias

CVALUES clause syntax is incorrect

DNo error, query is valid

Step-by-Step Solution

Solution:

Step 1: Count columns in VALUES and aliases
VALUES has 2 columns per row, but aliasing specifies 3 columns (id, letter, extra).
Step 2: Understand alias column count mismatch
PostgreSQL requires the number of alias columns to match the number of columns in VALUES exactly.
Final Answer:
Too many column aliases for the number of columns in VALUES -> Option A
Quick Check:
Alias columns must match VALUES columns count [OK]

Quick Trick: Alias columns count must equal VALUES columns count [OK]

Common Mistakes:

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Identify the error in this query: