SQL Server/T-SQL/Trigger/Create Trigger
Creating and Using Triggers
<source lang="sql">
1> create table employee( 2> ID int, 3> name nvarchar (10), 4> salary int, 5> start_date datetime, 6> city nvarchar (10), 7> region char (1)) 8> GO 1> 2> insert into employee (ID, name, salary, start_date, city, region) 3> values (1, "Jason", 40420, "02/01/94", "New York", "W") 4> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (2, "Robert",14420, "01/02/95", "Vancouver","N") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (3, "Celia", 24020, "12/03/96", "Toronto", "W") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (4, "Linda", 40620, "11/04/97", "New York", "N") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (5, "David", 80026, "10/05/98", "Vancouver","W") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (6, "James", 70060, "09/06/99", "Toronto", "N") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (7, "Alison",90620, "08/07/00", "New York", "W") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (8, "Chris", 26020, "07/08/01", "Vancouver","N") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (9, "Mary", 60020, "06/09/02", "Toronto", "W") 3> GO (1 rows affected) 1> 2> select * from employee 3> GO ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
1 Jason 40420 1994-02-01 00:00:00.000 New York W
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
7 Alison 90620 2000-08-07 00:00:00.000 New York W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W
(9 rows affected) 1> 2> -- Creating and Using Triggers 3> 4> 5> CREATE TRIGGER myTrigger 6> ON employee 7> FOR UPDATE, INSERT, DELETE 8> AS 9> SELECT * FROM inserted 10> SELECT * FROM deleted 11> GO 1> 2> 3> SELECT "Before INSERT" 4> INSERT Employee (ID, Name) VALUES (31, "Rick") 5> GO
Before INSERT (1 rows affected) ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
31 Rick NULL NULL NULL NULL
(1 rows affected) ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
(0 rows affected) 1> 2> SELECT "Before UPDATE" 3> UPDATE Employee 4> SET Name = "Rickie" 5> WHERE ID = 3 6> GO
Before UPDATE (1 rows affected) ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
3 Rickie 24020 1996-12-03 00:00:00.000 Toronto W
(1 rows affected) ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
(1 rows affected) 1> 2> SELECT "Before DELETE" 3> DELETE FROM Employee WHERE ID = 3 4> GO
Before DELETE (1 rows affected) ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
(0 rows affected) ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
3 Rickie 24020 1996-12-03 00:00:00.000 Toronto W
(1 rows affected) 1> 2> 3> drop table employee 4> GO 1>
</source>
Creating a Trigger and raise an error
<source lang="sql">
1> create table employee( 2> ID int, 3> name nvarchar (10), 4> salary int ) 5> GO 1> 2> create table job( 3> ID int, 4> title nvarchar (10), 5> averageSalary int) 6> GO 1> 2> 3> insert into employee (ID, name, salary) values (1, "Jason", 1234) 4> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (2, "Robert", 4321) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (3, "Celia", 5432) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (4, "Linda", 3456) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (5, "David", 7654) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (6, "James", 4567) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (7, "Alison", 8744) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (8, "Chris", 9875) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (9, "Mary", 2345) 2> GO (1 rows affected) 1> 2> insert into job(ID, title, averageSalary) values(1,"Developer",3000) 3> GO (1 rows affected) 1> insert into job(ID, title, averageSalary) values(2,"Tester", 4000) 2> GO (1 rows affected) 1> insert into job(ID, title, averageSalary) values(3,"Designer", 5000) 2> GO (1 rows affected) 1> insert into job(ID, title, averageSalary) values(4,"Programmer", 6000) 2> GO (1 rows affected) 1> 2> 3> select * from employee; 4> GO ID name salary
---------- -----------
1 Jason 1234
2 Robert 4321
3 Celia 5432
4 Linda 3456
5 David 7654
6 James 4567
7 Alison 8744
8 Chris 9875
9 Mary 2345
(9 rows affected) 1> select * from job; 2> GO ID title averageSalary
---------- -------------
1 Developer 3000
2 Tester 4000
3 Designer 5000
4 Programmer 6000
(4 rows affected) 1> 2> 3> -- Creating a Trigger 4> 5> CREATE TRIGGER tr_DelData 6> ON Employee 7> FOR DELETE 8> AS 9> IF (SELECT Count(*) FROM job) > 0 10> BEGIN 11> RAISERROR 50009 "Cannot delete an employee" 12> ROLLBACK TRANSACTION 13> RETURN 14> END 15> GO 1> 2> delete employee 3> GO Msg 50009, Level 16, State 1, Server sqle\SQLEXPRESS, Procedure tr_DelData, Line 11 Cannot delete an employee Msg 3609, Level 16, State 1, Server sqle\SQLEXPRESS, Line 2 The transaction ended in the trigger. The batch has been aborted. 1> 2> select * from employee 3> GO ID name salary
---------- -----------
1 Jason 1234
2 Robert 4321
3 Celia 5432
4 Linda 3456
5 David 7654
6 James 4567
7 Alison 8744
8 Chris 9875
9 Mary 2345
(9 rows affected) 1> 2> drop trigger tr_DelData 3> drop table employee; 4> drop table job; 5> GO 1>
</source>
Rolling Back in an AFTER Trigger
<source lang="sql">
1> create table employee( 2> ID int, 3> name nvarchar (10), 4> salary int, 5> start_date datetime, 6> city nvarchar (10), 7> region char (1)) 8> GO 1> 2> insert into employee (ID, name, salary, start_date, city, region) 3> values (1, "Jason", 40420, "02/01/94", "New York", "W") 4> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (2, "Robert",14420, "01/02/95", "Vancouver","N") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (3, "Celia", 24020, "12/03/96", "Toronto", "W") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (4, "Linda", 40620, "11/04/97", "New York", "N") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (5, "David", 80026, "10/05/98", "Vancouver","W") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (6, "James", 70060, "09/06/99", "Toronto", "N") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (7, "Alison",90620, "08/07/00", "New York", "W") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (8, "Chris", 26020, "07/08/01", "Vancouver","N") 3> GO (1 rows affected) 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (9, "Mary", 60020, "06/09/02", "Toronto", "W") 3> GO (1 rows affected) 1> 2> select * from employee 3> GO ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
1 Jason 40420 1994-02-01 00:00:00.000 New York W
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
7 Alison 90620 2000-08-07 00:00:00.000 New York W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W
(9 rows affected) 1> 2> --Rolling Back in an AFTER Trigger 3> 4> CREATE TRIGGER myTriggerRollback 5> ON Employee 6> FOR INSERT 7> AS 8> ROLLBACK TRAN 9> PRINT "INSERT statement rolled back." 10> GO 1> 2> DISABLE TRIGGER myTriggerRollback ON Employee 3> 4> SELECT * FROM Employee 5> 6> INSERT Employee (ID, Name) VALUES (31, "Rick") 7> 8> SELECT * FROM Employee 9> 10> DELETE FROM Employee WHERE ID = 31 11> GO ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
1 Jason 40420 1994-02-01 00:00:00.000 New York W
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
7 Alison 90620 2000-08-07 00:00:00.000 New York W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W
(1 rows affected) ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
1 Jason 40420 1994-02-01 00:00:00.000 New York W
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
7 Alison 90620 2000-08-07 00:00:00.000 New York W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W
31 Rick NULL NULL NULL NULL
(1 rows affected) 1> 2> ENABLE TRIGGER myTriggerRollback ON Employee 3> 4> SELECT * FROM Employee 5> 6> INSERT Employee (ID, Name) VALUES (31, "Rick") 7> GO ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
1 Jason 40420 1994-02-01 00:00:00.000 New York W
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
7 Alison 90620 2000-08-07 00:00:00.000 New York W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W
INSERT statement rolled back. Msg 3609, Level 16, State 1, Server sqle\SQLEXPRESS, Line 6 The transaction ended in the trigger. The batch has been aborted. (9 rows affected) 1> SELECT * FROM Employee 2> GO ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
1 Jason 40420 1994-02-01 00:00:00.000 New York W
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
7 Alison 90620 2000-08-07 00:00:00.000 New York W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W
(9 rows affected) 1> 2> drop table employee 3> GO 1>
</source>
