[Solved] Consider the table tasks(id INT, status TEXT) with rows:(1, 'pending'), (2, 'done'), (3, 'pending')What will this query return?DELETE FROM tasks WHERE status = 'pending' RETURNING id; | PostgreSQL

PostgreSQL - Set Operations and Advanced Queries

Consider the table tasks(id INT, status TEXT) with rows:
(1, 'pending'), (2, 'done'), (3, 'pending')
What will this query return?
DELETE FROM tasks WHERE status = 'pending' RETURNING id;

A(1), (2), (3)

B(2)

C(1), (3)

DNo rows returned

Step-by-Step Solution

Solution:

Step 1: Identify rows matching DELETE condition
Rows with status 'pending' are id 1 and 3.
Step 2: Understand RETURNING output
RETURNING id returns the ids of deleted rows, which are 1 and 3.
Final Answer:
(1), (3) -> Option C
Quick Check:
DELETE RETURNING returns deleted rows only [OK]

Quick Trick: RETURNING shows deleted rows matching WHERE [OK]

Common Mistakes:

Expecting rows with status 'done' to be deleted
Assuming all rows are returned
Ignoring WHERE clause in DELETE

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Consider the table tasks(id INT, status TEXT) with rows:

Step 1: Identify rows matching DELETE condition

Step 2: Understand RETURNING output

Final Answer:

Quick Check:

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