The deleted and inserted Logical Tables

deleted and inserted are logical (conceptual) tables. They are structurally identical to the table for which the trigger is defined—that is, the table on which the user action is attempted—and hold the old values or new values of the rows that would be changed by the user action.

Note: Both inserted and deleted tables appear as views on the transaction log, but they are fake tables on syslogs.

deleted and inserted tables can be examined by the trigger to determine whether or how the trigger action should be carried out, but the tables themselves cannot be altered by the trigger’s actions.

deleted tables are used with delete and update; inserted tables, with insert and update. An update is a delete followed by an insert: it affects the deleted table first, and then the inserted table.