[Solved] Given this transaction in PostgreSQL:BEGIN ISOLATION LEVEL REPEATABLE READ; UPDATE products SET stock = stock - 1 WHERE id = 10; SELECT stock FROM products WHERE id = 10; COMMIT;But you get an error:... | PostgreSQL

PostgreSQL - Transactions and Concurrency

Given this transaction in PostgreSQL:

BEGIN ISOLATION LEVEL REPEATABLE READ;
UPDATE products SET stock = stock - 1 WHERE id = 10;
SELECT stock FROM products WHERE id = 10;
COMMIT;

But you get an error: ERROR: syntax error at or near "ISOLATION". What is the fix?

AChange to <code>BEGIN; SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;</code>

BRemove the isolation level, just use <code>BEGIN;</code>

CUse <code>START TRANSACTION ISOLATION LEVEL REPEATABLE READ;</code>

DUse <code>SET SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL REPEATABLE READ;</code> before BEGIN

Step-by-Step Solution

Solution:

Step 1: Identify syntax error cause
PostgreSQL does not support specifying isolation level directly in BEGIN statement.
Step 2: Correct syntax to set isolation level
You must first BEGIN; then run SET TRANSACTION ISOLATION LEVEL REPEATABLE READ; before queries.
Final Answer:
Change to BEGIN; SET TRANSACTION ISOLATION LEVEL REPEATABLE READ; -> Option A
Quick Check:
Set isolation after BEGIN, not inside [OK]

Quick Trick: Set isolation after BEGIN with SET TRANSACTION [OK]

Common Mistakes:

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Given this transaction in PostgreSQL: