[Solved] Which of the following is the correct syntax to lock rows for update in PostgreSQL? — Ans: SELECT * FROM employees FOR UPDATE; | PostgreSQL

PostgreSQL - Transactions and Concurrency

Which of the following is the correct syntax to lock rows for update in PostgreSQL?

ASELECT * FROM employees FOR LOCK UPDATE;

BSELECT * FROM employees LOCK UPDATE;

CSELECT * FROM employees WITH UPDATE LOCK;

DSELECT * FROM employees FOR UPDATE;

Step-by-Step Solution

Solution:

Step 1: Recall the standard syntax for row-level locking
The correct syntax uses FOR UPDATE immediately after the FROM clause.
Step 2: Check each option for syntax correctness
Only SELECT * FROM employees FOR UPDATE; matches the correct PostgreSQL syntax.
Final Answer:
SELECT * FROM employees FOR UPDATE; -> Option D
Quick Check:
Correct syntax for locking rows = SELECT * FROM employees FOR UPDATE; [OK]

Quick Trick: Use FOR UPDATE right after FROM clause to lock rows [OK]

Common Mistakes:

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Which of the following is the correct syntax to lock rows for update in PostgreSQL?