Can you name different levels of transaction isolation in databases?

Databases typically distinguish four main levels of transaction isolation, which determine how transactions see each other's changes:

1. Read Uncommitted — a transaction can see changes made by other transactions even if they haven't been committed. Dirty reads are possible.

2. Read Committed — a transaction only sees data that has been committed by other transactions. It prevents dirty reads but allows non-repeatable reads.

3. Repeatable Read — guarantees that if a transaction reads data, it will see the same data if it reads again. It prevents non-repeatable reads but allows phantom reads.

4. Serializable — the strictest level, transactions are executed as if they were sequential. It prevents all anomalies but reduces performance.

Example of setting the isolation level in C# using ADO.NET:

using (var connection = new SqlConnection(connectionString))
{
    connection.Open();
    using (var transaction = connection.BeginTransaction(IsolationLevel.Serializable))
    {
        // database operations
        transaction.Commit();
    }
}