Can you explain the concept of transaction isolation in database management systems?

Transaction isolation is one of the key properties of transactions in database management systems (DBMS), which guarantees that concurrently executing transactions do not affect each other, ensuring data integrity.

There are several levels of isolation defined by the SQL standard:

• Read Uncommitted: a transaction can see uncommitted changes made by other transactions (dirty read).
• Read Committed: a transaction only sees data that has been committed by other transactions.
• Repeatable Read: guarantees that data read by a transaction will not change until the transaction completes.
• Serializable: the strictest level, transactions are executed as if they were sequential, one after another.

Isolation helps prevent issues such as:

• dirty read,
• non-repeatable read,
• phantom read.

Example: if two transactions try to update the same account simultaneously, isolation guarantees that the changes will be applied sequentially, not mixed, preventing data loss.