[Solved] Which of the following is the correct syntax to alias columns when using the VALUES clause? — Ans: SELECT * FROM (VALUES (1, 'A'), (2, 'B')) AS t(id, letter); | PostgreSQL

PostgreSQL - Set Operations and Advanced Queries

Which of the following is the correct syntax to alias columns when using the VALUES clause?

ASELECT * FROM VALUES (1, 'A'), (2, 'B') AS t(id, letter);

BSELECT * FROM (VALUES (1, 'A'), (2, 'B')) AS t(id, letter, extra);

CSELECT * FROM (VALUES (1, 'A'), (2, 'B')) AS t(id);

DSELECT * FROM (VALUES (1, 'A'), (2, 'B')) AS t(id, letter);

Step-by-Step Solution

Solution:

Step 1: Understand aliasing syntax for VALUES
When aliasing columns, the syntax is AS alias_name(column1, column2) after the VALUES clause in parentheses.
Step 2: Validate each option
SELECT * FROM (VALUES (1, 'A'), (2, 'B')) AS t(id, letter); correctly aliases two columns. SELECT * FROM VALUES (1, 'A'), (2, 'B') AS t(id, letter); misses parentheses around VALUES. SELECT * FROM (VALUES (1, 'A'), (2, 'B')) AS t(id); aliases fewer columns than provided. SELECT * FROM (VALUES (1, 'A'), (2, 'B')) AS t(id, letter, extra); aliases more columns than provided.
Final Answer:
SELECT * FROM (VALUES (1, 'A'), (2, 'B')) AS t(id, letter); -> Option D
Quick Check:
Correct aliasing = AS alias(col1, col2) after VALUES [OK]

Quick Trick: Alias columns with AS alias(col1, col2) after VALUES [OK]

Common Mistakes:

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Which of the following is the correct syntax to alias columns when using the VALUES clause?