SQL Server-triggers for code offloading

2. trigger is a table of additions and deletions to the operation, causing or triggering the addition and deletion of another table operation, so the trigger has 3 deleted trigger, update trigger, insert trigger
4. triggers are replaced by The original addition and deletion of the operation, or in the original additions and deletions after the completion of the modification operation, divided into triggers and for or after Trigger ( for and after belongs to a trigger)
6. the use of triggers involves two very important tables that are used to hold records that have changed or that are not present on the table in which the first chapter was manipulated, namely virtual tables Inserted and Virtual Tables Deleted

	Virtual table inserted	Virtual table deleted
	Store the new record	Do not store records
	Store new records for update	Store pre-update records
When deleted	Do not store records	To store deleted records

1. here is an easy-to-understand example of a trigger that is used to reconstruct a personal version of a computer room fee system .
   1. before we removeT_onwork_infowhen working on a machine in a table,T_work_infotable to write the work record, and alsoT_admin_infoin the tableIsOnfield is changed toFalse

      CREATE TRIGGER Trigger_delonwork on T_onwork_info for DELETE as DECLARE @name varchar (TEN) DECLARE @loginDate varchar (TEN) DECLARE @loginTim e varchar (DECLARE) @logoutDate varchar (DECLARE @logoutTime varchar) DECLARE @comName varchar () SELECT @name = ( Select NAME from deleted) Select @loginDate = (select logindate from deleted)-----deleted table is used to store the deleted records in T_onwork table SELECT @lo Gintime = (select Logintime from deleted) SELECT @comName = (select Comname from deleted) SET @logoutDate =convert (varchar ( ), GETDATE (), 101) SET @logoutTime =convert (varchar (), GETDATE (), 108) if (SELECT COUNT (*) from deleted) =1 BEGIN INSERT I NTO t_work_info (name,logindate,logintime,logoutdate,logouttime,comname) VALUES (@name, @loginDate, @loginTime, @ Logoutdate, @logoutTime, @comName) UPDATE t_admin_info SET ison= ' False ' WHERE name= (SELECT Name from deleted) ROLLBACK TRA N--Transaction rollback END 

      How about, the trigger is very simple, you can try to use, trigger+the rollback mechanism of a transaction makes it easy to offload the code