week 10

10.5 Transaction Isolation Levels

SQL defines four standard isolation levels, representing trade-offs between consistency and concurrency:

Isolation Level	Concurrency Problems Prevented	Nigerian Bank Use Case
READ UNCOMMITTED	None (allows all problems)	Almost never used in banking — too risky
READ COMMITTED	Prevents Dirty Reads	Default in Oracle, PostgreSQL. Used for routine banking queries where slight inconsistency is acceptable.
REPEATABLE READ	Prevents Dirty Reads + Non-Repeatable Reads	Default in MySQL InnoDB. Good for financial reporting within a transaction.
SERIALIZABLE	Prevents ALL problems (full isolation)	Used for critical financial operations: salary payments, regulatory reporting, inter-bank transfers.

SQL: SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;