Hi guys i AM trying to do a trigger statement (i havnt done any before) so i am basically looking to insert values into a table and m using the following code but its not working any help will be do me good thanks in advance: code m using is following:
CREATE TRIGGER updatemovie
ON movies
FOR INSERT
AS
BEGIN
INSERT INTO movies values (
movieID, movieName, movieTime, movieDate, movieTime, movieType, Duration, ratings)
END
table i am looking to update is:
CREATE TABLE movies(
movieID int IDENTITY (1,1)NOT NULL,
movieName varchar (50),
movieTime Time,
movieDate Date,
movieType varchar (20),
duration varchar (10),
rating varchar (10),
PRIMARY KEY (perID),
);
A trigger will allow you to either cancel the update/insert/delete depending on a condition or it will allow you to keep a record of the update/insert/delete. So if you have a second table (audit ) you can do the following:
update/insert/delete
CREATE TRIGGER updatemovie
ON movies
FOR INSERT
AS
BEGIN
INSERT INTO movies_audit values (
inserted.movieID, inserted.movieName, inserted.movieTime, inserted.movieDate, inserted.movieTime, inserted.movieType, inserted.Duration, inserted.ratings)
END
The inserted table is created automatically and contains (for the duration of the trigger) the rows that were just inserted.
Related
I need to create a new DATETIME column in SQL Server that will always contain the date of when the record was created, and then it needs to automatically update whenever the record is modified. I've heard people say I need a trigger, which is fine, but I don't know how to write it. Could somebody help with the syntax for a trigger to accomplish this?
In MySQL terms, it should do exactly the same as this MySQL statement:
ADD `modstamp` timestamp NULL
DEFAULT CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP
Here are a few requirements:
I can't alter my UPDATE statements to set the field when the row is modified, because I don't control the application logic that writes to the records.
Ideally, I would not need to know the names of any other columns in the table (such as the primary key)
It should be short and efficient, because it will happen very often.
SQL Server doesn't have a way to define a default value for UPDATE.
So you need to add a column with default value for inserting:
ADD modstamp DATETIME2 NULL DEFAULT GETDATE()
And add a trigger on that table:
CREATE TRIGGER tgr_modstamp
ON **TABLENAME**
AFTER UPDATE AS
UPDATE **TABLENAME**
SET ModStamp = GETDATE()
WHERE **ID** IN (SELECT DISTINCT **ID** FROM Inserted)
And yes, you need to specify a identity column for each trigger.
CAUTION: take care when inserting columns on tables where you don't know the code of the application. If your app have INSERT VALUES command without column definition, it will raise errors even with default value on new columns.
This is possible since SQL Server 2016 by using PERIOD FOR SYSTEM_TIME.
This is something that was introduced for temporal tables but you don't have to use temporal tables to use this.
An example is below
CREATE TABLE dbo.YourTable
(
FooId INT PRIMARY KEY CLUSTERED,
FooName VARCHAR(50) NOT NULL,
modstamp DATETIME2 GENERATED ALWAYS AS ROW START NOT NULL,
MaxDateTime2 DATETIME2 GENERATED ALWAYS AS ROW END HIDDEN NOT NULL,
PERIOD FOR SYSTEM_TIME (modstamp,MaxDateTime2)
)
INSERT INTO dbo.YourTable (FooId, FooName)
VALUES (1,'abc');
SELECT *
FROM dbo.YourTable;
WAITFOR DELAY '00:00:05'
UPDATE dbo.YourTable
SET FooName = 'xyz'
WHERE FooId = 1;
SELECT *
FROM dbo.YourTable;
DROP TABLE dbo.YourTable;
It has some limitations.
The time stored will be updated by the system and always be UTC.
There is a need to declare a second column (MaxDateTime2 above) that is completely superfluous for this use case. But it can be marked as hidden making it easier to ignore.
Okay, I always like to keep track of not only when something happened but who did it!
Lets create a test table in [tempdb] named [dwarfs]. At a prior job, a financial institution, we keep track of inserted (create) date and updated (modify) date.
-- just playing
use tempdb;
go
-- drop table
if object_id('dwarfs') > 0
drop table dwarfs
go
-- create table
create table dwarfs
(
asigned_id int identity(1,1),
full_name varchar(16),
ins_date datetime,
ins_name sysname,
upd_date datetime,
upd_name sysname,
);
go
-- insert/update dates
alter table dwarfs
add constraint [df_ins_date] default (getdate()) for ins_date;
alter table dwarfs
add constraint [df_upd_date] default (getdate()) for upd_date;
-- insert/update names
alter table dwarfs
add constraint [df_ins_name] default (coalesce(suser_sname(),'?')) for ins_name;
alter table dwarfs
add constraint [df_upd_name] default (coalesce(suser_sname(),'?')) for upd_name;
go
For updates, but the inserted and deleted tables exist. I choose to join on the inserted for the update.
-- create the update trigger
create trigger trg_changed_info on dbo.dwarfs
for update
as
begin
-- nothing to do?
if (##rowcount = 0)
return;
update d
set
upd_date = getdate(),
upd_name = (coalesce(suser_sname(),'?'))
from
dwarfs d join inserted i
on
d.asigned_id = i.asigned_id;
end
go
Last but not least, lets test the code. Anyone can type a untested TSQL statement in. However, I always stress testing to my team!
-- remove data
truncate table dwarfs;
go
-- add data
insert into dwarfs (full_name) values
('bilbo baggins'),
('gandalf the grey');
go
-- show the data
select * from dwarfs;
-- update data
update dwarfs
set full_name = 'gandalf'
where asigned_id = 2;
-- show the data
select * from dwarfs;
The output. I only waited 10 seconds between the insert and the delete. Nice thing is that who and when are both captured.
Create trigger tr_somename
On table_name
For update
As
Begin
Set nocount on;
Update t
Set t.field_name = getdate()
From table_name t inner join inserted I
On t.pk_column = I.pk_column
End
ALTER TRIGGER [trg_table_name_Modified]
ON [table_name]
AFTER UPDATE
AS
Begin
UPDATE table_name
SET modified_dt_tm = GETDATE() -- or use SYSDATETIME() for 2008 and newer
FROM Inserted i
WHERE i.ID = table_name.id
end
I have one table called [FridgeTemperture], when any record inserted it should add one value in the new table MpSensors. But records are not being inserted in the new table when a record is inserted.
Error
Explicit value must be specified for identity column in table
'MpSensors' either identity_insert is set to ON or when a replication
user is inserting into a not for replication identity column.
CREATE TRIGGER [dbo].[FridgeTemperature_INSERT]
ON [dbo].[FridgeTemperture]
AFTER INSERT
AS
BEGIN
SET IDENTITY_INSERT MpSensors ON;
SET NOCOUNT ON;
DECLARE #fridge_temp varchar(10)
INSERT INTO MpSensors(fridge_temp)
VALUES(#fridge_temp)
SET IDENTITY_INSERT MpSensors OFF;
END
GO
table schema
CREATE TABLE [dbo].[MpSensors](
[id] [int] IDENTITY(1,1) NOT NULL,
[fridge_temp] [varchar](10) NULL
) ON [PRIMARY]
CREATE TABLE [dbo].[FridgeTemperture](
[Id] [int] IDENTITY(1,1) NOT NULL,
[ShopId] [nvarchar](4) NULL,
[Fridgetemp] [decimal](4, 2) NOT NULL,
[UpdatedDate] [datetime2](7) NOT NULL
GO
You don't need the set identity_insert on if you are not attempting to insert values to the identity column. Also, your current insert statement, if you loose the set identity_insert, will simply inside a single null row for any insert statement completed successfully on the FridgeTemperture table.
When using triggers, you have access to the records effected by the statement that fired the trigger via the auto-generated tables called inserted and deleted.
I think you are after something like this:
CREATE TRIGGER [dbo].[FridgeTemperature_INSERT]
ON [dbo].[FridgeTemperture]
AFTER INSERT
AS
BEGIN
INSERT INTO MpSensors(fridge_temp)
SELECT CAST(Fridgetemp as varchar(10))
FROM inserted
END
Though I can't really see any benefit of storing the same value in two different places, and in two different data types.
Update
Following our conversation in the comments, you can simply use an update statement in the trigger instead of an insert statement:
UPDATE MpSensors
SET fridge_temp = (
SELECT TOP 1 CAST(Fridgetemp as varchar(10))
FROM inserted
ORDER BY Id DESC
)
This should give you the latest record in case you have an insert statement that inserts more than a single record into the FridgeTemperture table in a single statement.
create TRIGGER [dbo].[FridgeTemperature_INSERT]
ON [dbo].[FridgeTemperture]
AFTER INSERT
AS
BEGIN
UPDATE MpSensors
SET fridge_temp = CAST(Fridgetemp as varchar(10))
FROM inserted
END
You need to use Select statement with CAST as [fridge_temp] is varchar in MpSensors table in Trigger. Try like this:
CREATE trigger <table_name>
ON <table_name>
AFTER Insert
AS
BEGIN
INSERT INTO <table_name>(column_name)
Select CAST(column_name as varchar(10))
FROM inserted
END
The inserted table stores copies of the affected rows during INSERT and UPDATE statements. During an insert or update transaction, new rows are added to both the inserted table and the trigger table. The rows in the inserted table are copies of the new rows in the trigger table.
I need to insert records into a production table. The problem is that one of the fields needs to be the same value as the primary key.
In the example below, the Insert query is dropping '99' into [AlsoMyID]. But that's just a placeholder. It needs to be whatever value is going into [MyID].
How do I write the Insert query so that the system will add the same PK value to both [MyID] and [AlsoMyID]?
Drop table #mylittletable
Create table #Mylittletable (
[MyID] int IDENTITY(1,1) NOT FOR REPLICATION NOT NULL,
[AlsoMyID] int,
[ActualData] varchar(1))
Select * from #Mylittletable
Insert into #Mylittletable values (99,'x')
Select * from #Mylittletable
If you're interested in the background, the developer is using AlsoMyID as a linking field so any number of records can be linked together using the original primary key value. That said, I have no control over the table structure.
Firstly, you cannot specify the value for identity column unless you use set identity_insert on. so according to your requirement, you need to insert the same value to AlsoMyID as MyID.
You can work it out as flowing:
insert into Mylittletable
select ##IDENTITY+1,'1'
With this trigger on the table you can insert anything on the alsoMyID-column and that will be overwritten with what get's set in the myID-column.
create trigger tr_Mylittletable ON Mylittletable
AFTER INSERT AS
BEGIN
declare #ID int = (select MyID from inserted)
update Mylittletable set AlsoMyID = #ID where MyID = #ID
END
NOTE: This only works when making inserts of one line at a time!
Is there a way so that in a CREATE TABLE table ( ... ) I can force a procedure or a function to run on every insert?
-- For exmaple:
CREATE TABLE table (
ID INT IDENTITY (1,1) PRIMARY KEY,
Pass varchar(200) -- Can I do Proc(Pass) to return the output instead?
)
You can run a trigger on every new insert and do what you want..You have access to virtual table called inserted inside trigger which contains inserted values
Create trigger name
on tbl
after insert
as
begin
---select * from inserted
--your proc here
end
You might also take a look at computed columns. They are virtual columns in a table computed by an expression defined when the table is created. E.g.:
CREATE TABLE products
(id INT,
price MONEY,
tax AS price * .15);
-- the column tax is computed as 15% of the price whenever a price is changed (inserts or updates). Though having limitations they come in handy in simple cases.
I have a table containing id, user_Name and password. I want to create the trigger which will fire when ever the password changes.
Suppose the table is:
create table reg
(
id int identity(1,1) primary key,
userName varchar(100),
pass varchar(100)
)
and I want to save userName, password, changeDate in to below table
create table regBackUp
(
id int identity(1,1),
regId foreign key references reg(id),
oldPass varchar(100),
changeDate date
)
Well, you need to create after update trigger on reg table.
In that trigger you need to write to table regBackUp records selected from table named deleted. It is special table available in that triggers and it will hold values of reg table just before update.
See MSDN for reference about syntax of create trigger expression.
Use this. TRIGGER
You can get the old values from DELETED table
CREATE TRIGGER trgTest ON regFOR UPDATE
AS
BEGIN
IF UPDATE(pass)
BEGIN
DECLARE #id AS INT
DECLARE #pass AS varchar(100)
SELECT #id = ID, #pass = pass FROM DELETED
INSERT INTO regBackUp (regId, oldPass, changeDate)
VALUES (#id, #pass, GETDATE())
END
END
Use After Update Trigger with Update() function to find out whether column is updated or not. From docs.
indicates whether an INSERT or UPDATE attempt was made on a specified
column of a table or view. UPDATE() is used anywhere inside the body
of a Transact-SQL INSERT or UPDATE trigger to test whether the trigger
should execute certain actions.
Create a After Update trigger like this.
CREATE TRIGGER reg_pass_trg
ON reg
after UPDATE
AS
BEGIN
IF UPDATE(pass) --Works only when pass is mentioned in update statement
INSERT INTO regBackUp
(regId,oldPass,changeDate)
SELECT ID,pass,Getdate()
FROM deleted
END
INSERT INTO namepassback
(username,
pass,
[date])
SELECT username,
pass,
Getdate()
FROM namepass
WHERE id = 1
use above query that will work same without creating trigger