what is a concrete implementation I can use for isolating transactions? For example, for atomicity, I can lump multiple statements underneath a BEGIN TRAN and then call COMMIT somewhere down the line. For consistency, I can set types for columns as well as constraints. For durability, I can set a trigger to archive records onto another table, schedule backup jobs or manually back records up myself. What can I do for isolation? Is locking a table a way to achieve this? Do I need to understand what a database “session” is for me to make sense of isolation?