[Solved] Given the table employees(id INT, salary INT) with rows:(1, 5000), (2, 6000), (3, 7000)What will be the output of:UPDATE employees SET salary = salary + 500 WHERE id | PostgreSQL

PostgreSQL - Set Operations and Advanced Queries

Given the table employees(id INT, salary INT) with rows:
(1, 5000), (2, 6000), (3, 7000)
What will be the output of:
UPDATE employees SET salary = salary + 500 WHERE id <= 2 RETURNING id, salary;

A(1, 5500), (2, 6500), (3, 7000)

BNo rows returned

C(3, 7000)

D(1, 5500), (2, 6500)

Step-by-Step Solution

Solution:

Step 1: Identify rows matching WHERE condition
Rows with id 1 and 2 satisfy id <= 2.
Step 2: Calculate updated salaries and returned rows
Salary for id 1 becomes 5000 + 500 = 5500, for id 2 becomes 6000 + 500 = 6500. Only these rows are returned.
Final Answer:
(1, 5500), (2, 6500) -> Option D
Quick Check:
RETURNING outputs updated rows only [OK]

Quick Trick: RETURNING shows only rows matching WHERE and updated [OK]

Common Mistakes:

Expecting all rows returned
Ignoring WHERE clause
Assuming unchanged rows are returned

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Given the table employees(id INT, salary INT) with rows:

Step 1: Identify rows matching WHERE condition

Step 2: Calculate updated salaries and returned rows

Final Answer:

Quick Check:

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