The following are the different transaction levels in SQL Server with their syntax to set them:
1. READ COMMITTED
Syntax : SET TRANSACTION ISOLATION LEVEL READ COMMITTED
2. READ UNCOMMITTED
Syntax : SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED
3. REPEATABLE READ
Syntax : SET TRANSACTION ISOLATION LEVEL REPEATABLE READ
4. SERIALIZABLE
Syntax : SET TRANSACTION ISOLATION LEVEL SERIALIZABLE