Briefly describe the three states of Insert,update,delete within SQL Server triggers

Three kinds of insert,update,delete states in a trigger

CREATE TRIGGER tr_t_a on t_a for Insert,update,delete

if exists (select * from inserted) and NOT EXISTS (SELECT * from deleted) is an INSERT

if exists (select * from inserted) and exists (SELECT * from deleted) is UPDATE

if exists (select * from deleted) and NOT EXISTS (SELECT * from inserted) is DELETE

Insert Action: Inserted table has data, deleted table has no data

Delete action (delete): Inserted table has no data, deleted table has data

Update: Inserted table has data (new data), deleted table has data (old data)

The author uses the case:

Create TRIGGER [risk]. [Entry_head_port_exchange_trigger]

On [RiskH800]. [Risk]. [Entry_head]

After Insert,update

As

DECLARE @COUNT INT

DECLARE @MANUAL_NO_COUNT INT

IF EXISTS (SELECT 1 from INSERTED)

IF EXISTS (SELECT 1 from DELETED)

BEGIN

SELECT @COUNT = COUNT (*) from risk. Entry_head_port_exchange WHERE entry_id = (select entry_id from DELETED)

SELECT @MANUAL_NO_COUNT = COUNT (manual_no) from DELETED where substring (manual_no,1,1) = ' B ' or substring (manual_no,1,1) = C

IF @COUNT <=0 and @MANUAL_NO_COUNT >0

INSERT into risk. Entry_head_port_exchange (entry_id,create_date) (SELECT entry_id,getdate () from DELETED)

End

ELSE

BEGIN

SELECT @COUNT = COUNT (*) from risk. Entry_head_port_exchange WHERE entry_id = (select entry_id from INSERTED)

SELECT @MANUAL_NO_COUNT = COUNT (manual_no) from INSERTED where substring (manual_no,1,1) = ' B ' or substring (manual_no,1,1) = ' C '

IF @COUNT <=0 and @MANUAL_NO_COUNT >0

INSERT into risk. Entry_head_port_exchange (entry_id,create_date) (SELECT entry_id,getdate () from INSERTED)

End