"2018-01-19" SQL server-Trigger

1 --CREATE table users--Creating user tables2 --(3 --IDs int primary key identity (.),4 --name nvarchar,--names5 --class nvarchar (200)--Class number6 --)7 8 --CREATE table class--Creating a class table9 --(Ten --classcode nvarchar ($) primary key,--class number One --className nvarchar (,--class name) A --) -  - ----Insert class table data the --INSERT into class values (' c001 ', ' one Shift '); - --INSERT into class values (' c002 ', ' Class Two '); - --INSERT into class values (' c003 ', ' class Three '); - --INSERT into class values (' c004 ', ' Class Four '); + --INSERT into class values (' c005 ', ' five classes '); - ----Insert User table data + --INSERT into users values (' Zhang Yi ', ' c001 '); A --INSERT into users values (' Zhang Yi ', ' c002 '); at --INSERT into users values (' Zhang San ', ' c003 '); - --INSERT into users values (' Zhang Si ', ' c004 '); - --INSERT into users values (' Five ', ' c005 '); -  - --select * from users; - --SELECT * from class; in  - ----Trigger to ----(a special stored procedure, no way to call it directly, but by adding or deleting the action to trigger it + ----One action on a table can only have one trigger) - Create TriggerUsers_delete the  onUsers *  for Delete--perform a delete operation to trigger, and then perform the following actions $  asPanax Notoginseng Select *  fromUsers -  the  + Create TriggerUsers_insert A  onUsers the  for Insert--perform an insert operation to trigger and then perform the Operation +  as - Select *  fromUsers $  $ Create TriggerUsers_delete -  onUsers -instead of Delete--When you perform a delete operation, the operation is not performed and the following actions replace the  as - Select *  fromUsersWuyi  the Create TriggerUsers_delete -  onUsers Wuinstead of Delete -  as About Select *  fromDeleted--querying for deleted data $  -  - Create TriggerUsers_delete -  onUsers Ainstead of Delete +  as the     Declare @a nvarchar( -) -     Select @a=Ids fromdeleted $     if @a=2 the     begin the         Select 'It 's too ugly to be deleted! ' the     End the     Else -     begin in         Delete  fromUserswhereIds=@a the     End the      About Delete  fromUserswhereIds=2 the  the  the  + ----Cascade Delete - Create TriggerClass_delete the  onclassBayiinstead of Delete the  as the     Declare @a nvarchar( $); -     Select @a=Classcode fromdeleted; -     Delete  fromUserswhereClass=@a; the     Delete  fromClasswhereClasscode=@a; the      the Delete  fromClasswhereClasscode='c001';

"2018-01-19" SQL server-Trigger