Do you remember the levels of transaction isolation?

Transaction isolation levels determine how and when the changes made by one transaction become visible to other transactions. The main isolation levels in DBMS:

• Read Uncommitted — the lowest isolation level. A transaction can read data that has been modified but not yet committed (dirty read).
• Read Committed — a transaction only sees committed data. Dirty reads are prevented, but non-repeatable reads and phantom reads can occur.
• Repeatable Read — guarantees that data read by a transaction will not change until it completes. Non-repeatable reads are prevented, but phantom reads can occur.
• Serializable — the strictest level. Transactions are executed as if they were sequential, fully preventing phantom reads.

In C#, when working with TransactionScope or SqlTransaction, you can specify the isolation level using the IsolationLevel parameter.