Determines whether the trigger is processing insert, delete, or update.

However, sometimes, you can view the logic of the process and write the three into a trigger, only to make a slight judgment.

You can determine from the following method whether the trigger is triggered by processing the insert, delete, or update:

Copy codeThe Code is as follows:
-- Declare two variables
DECLARE @ d bit = 0
DECLARE @ I BIT = 0

-- If a record is found in the temporary trigger table of DELETED, the old data is DELETED.
If exists (select top 1 1 from deleted)
SET @ D = 1

-- If a record is found in the temporary trigger table of INSERTED, new data is INSERTED.
If exists (select top 1 1 from inserted)
SET @ I = 1

-- If both tables have records, the trigger is triggered by an update.
IF @ I = 1 AND @ D = 1
PRINT (n' update. ')

-- If the variable @ I is changed to 1, and the variable @ D is not changed, the trigger is triggered by executing the insert operation.
IF @ I = 1 AND @ D = 0
PRINT (n'insert ')

-- The following judgment is true, indicating that the trigger is triggered when the deletion is executed.
IF @ I = 0 AND @ D = 1
PRINT (n'delete ')


In addition, there are two temporary internal trigger tables, the Inserted Table of the trigger and the Deleted table.

The trigger has two virtual tables: The Inserted Table and the Deleted table. The two tables have different data statuses under different operations.
1. INSERT: The Inserted Table has data, and the Deleted table has no data.
2. UPDATE: The Inserted Table has data (new data) and the Deleted table has data (old data ).
Iii. DELETE: The Inserted Table has no data and the Deleted table has data.