I have a small performance issue with one of my database triggers in my MS-SQL Server 2014 database.
CREATE TRIGGER [dbo].[TRG_T_TPM_Vehicle_Update] ON [dbo].[T_TPM_Vehicle]
AFTER UPDATE
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
UPDATE T_TPM_Vehicle SET LastUpdated = getdate()
WHERE Vehicle_Number IN (SELECT Vehicle_Number FROM inserted)
UPDATE T_TPM_Vehicle SET [DisturbedSince] = getdate()
WHERE Vehicle_Number IN (SELECT Vehicle_Number FROM inserted WHERE inserted.Emergency_Stop = 1)
AND Vehicle_Number IN (SELECT Vehicle_Number FROM deleted WHERE deleted.Emergency_Stop = 0)
INSERT INTO T_TPM_Vehicle_HistoricalData
([Vehicle_Ref]
,[Vehicle_Number]
,[Vehicle_Type]
,[Pos_X]
,[Pos_Y]
,[Alpha]
,[LastAutoPos_X]
,[LastAutoPos_Y]
,[LastAutoAlpha]
,[Automatic]
,[Manual]
,[Blocked]
,[Loaded]
,[Stoped]
,[Emergency_Stop]
,[User_Required]
,[BatteryAlmostEmpty]
,[BatteryEmpty]
,[BatteryLevel]
,[ChargingRelaisEnable]
,[NavOK]
,[PowerOn]
,[Available]
,[OperatingMinutes]
,[UpdateOperatingMinutes]
,[DataChangedByVIS]
,[Blockingsreleased]
,[Cancelled]
,[ProductID]
,[HUIdent1]
,[HUIdent2]
,[HUType]
,[DisturbedSince])
SELECT inserted.[Vehicle_Ref]
,inserted.[Vehicle_Number]
,inserted.[Vehicle_Type]
,inserted.[Pos_X]
,inserted.[Pos_Y]
,inserted.[Alpha]
,inserted.[LastAutoPos_X]
,inserted.[LastAutoPos_Y]
,inserted.[LastAutoAlpha]
,inserted.[Automatic]
,inserted.[Manual]
,inserted.[Blocked]
,inserted.[Loaded]
,inserted.[Stoped]
,inserted.[Emergency_Stop]
,inserted.[User_Required]
,inserted.[BatteryAlmostEmpty]
,inserted.[BatteryEmpty]
,inserted.[BatteryLevel]
,inserted.[ChargingRelaisEnable]
,inserted.[NavOK]
,inserted.[PowerOn]
,inserted.[Available]
,inserted.[OperatingMinutes]
,inserted.[UpdateOperatingMinutes]
,inserted.[DataChangedByVIS]
,inserted.[Blockingsreleased]
,inserted.[Cancelled]
,inserted.[ProductID]
,inserted.[HUIdent1]
,inserted.[HUIdent2]
,inserted.[HUType]
,inserted.[DisturbedSince]
FROM inserted
END
What it basically does is it sets the LastUpdated column for all rows in inserted and the DisturbedSince column for a subset of the inserted rows.
Finally the inserted rows get copied to a history table. (Every change on any row must be saved for two days). Older data gets deleted by a maintenance job.
As we have up to ~ 300 rows updated per second (Updates to rows can be batched together) We create a big amount of data and recursive updates.
I've now found the INSTEAD OF UPDATE triggers which seem to solve the recursive UPDATE problem caused by my trigger but I would have to process every row of the inserted table one by one with an update statement in the trigger.
I'm not sure if this is really faster. Does anyone of you have a recommendation?
What I really need is to tweak / extend the data rows before they are send to the table. Is there an approach for this?
e.g.: Something like:
CREATE TRIGGER ... INSTEAD OF UPDATE
AS
BEGIN
UPDATE inserted SET LastUpdated = getdate()
UPDATE inserted SET DisturbedSince
WHERE Vehicle_Number IN (SELECT Vehicle_Number FROM inserted WHERE inserted.Emergency_Stop = 1)
AND Vehicle_Number IN (SELECT Vehicle_Number FROM deleted WHERE deleted.Emergency_Stop = 0)
"SAVE INSERTED"
END
and an AFTER UPDATE TRIGGER with the storage of the changed data to the history table.
Thank you for any suggestions.
Thomas
You're right to think that using an INSTEAD OF trigger is the right way to go rather than an AFTER trigger, when you're wanting to change data within the same table as well.
It would be something like:
CREATE TRIGGER [dbo].[TRG_T_TPM_Vehicle_Update] ON [dbo].[T_TPM_Vehicle]
INSTEAD OF UPDATE
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
UPDATE tgt
SET
Vehicle_Ref = i.Vehicle_Ref,
Vehicle_Type = i.Vehicle_Type,
...
LastUpdated = getdate(),
DisturbedSince = CASE WHEN i.Emergency_Stop=1 and d.Emergency_Stop=0
THEN getdate() ELSE d.DisturbedSince END
OUTPUT
inserted.[Vehicle_Ref]
,inserted.[Vehicle_Number]
,inserted.[Vehicle_Type]
...
,inserted.[HUIdent2]
,inserted.[HUType]
,inserted.[DisturbedSince]
INTO T_TPM_Vehicle_HistoricalData
([Vehicle_Ref]
,[Vehicle_Number]
,[Vehicle_Type]
...
,[HUIdent2]
,[HUType]
,[DisturbedSince])
FROM
T_TPM_Vehcile tgt
inner join
inserted i
on
tgt.Vehicle_Number = i.Vehicle_Number
inner join
deleted d
on
tgt.Vehicle_Number = d.Vehicle_Number
You'll note that I've combined both the UPDATEs and the INSERT into the history table into a single compound statement.
You'll also note that it's slightly confusing because there are two inserteds in play here - the inserted as part of the trigger (aliased as i to sidestep some of the confusion) and the inserted as part of the OUTPUT clause.
Related
I am trying to write an update trigger on a table which would cause it to run an additional update statement only if a certain column has been changed, so far the trigger runs the update no matter what, hoping maybe someone can see what I am doing wrong here.
Here is the trigger.
ALTER TRIGGER [dbo].[StatusChangedUpdateTrigger]
ON [dbo].[Trans_Order]
AFTER UPDATE
AS
DECLARE #OldOrderStatusId INT, #NewStatusOrderId INT, #ERRNUM INT;
BEGIN
SET #OldOrderStatusId = (SELECT OrderStatusId FROM deleted);
SET #NewStatusOrderId = (SELECT OrderStatusId FROM inserted);
IF (#OldOrderStatusId != #NewStatusOrderId)
SET NOCOUNT ON;
UPDATE Trans_Order
SET StatusChanged = 1
WHERE Id = (SELECT ID FROM inserted)
END
For some reason this is running no matter what, I can never set StatusChanged to 0 as it will automatically flip it back to 1 even if the OrderStatusId hasn't changed. So my update statement is running no matter what, so I am guessing I am doing something wrong in the if statement.
Hmmmm . . . Your logic seems strange. I would expect:
UPDATE t
SET StatusChanged = 1
FROM Trans_Order t JOIN
Inserted i
ON t.id = i.id JOIN
Deleted d
ON t.id = d.id
WHERE i.OrderStatusId <> d.OrderStatusId;
You might need to take NULL values into account -- although your code does not.
Note that your code is just a bug waiting to happen, because it assumes that inserted and deleted have only one row.
The specific problem with your code is that it is really:
IF (#OldOrderStatusId != #NewStatusOrderId)
BEGIN
SET NOCOUNT ON;
END;
UPDATE Trans_Order
SET StatusChanged = 1
WHERE Id = (SELECT ID FROM inserted);
Your indentation has confused the logic. However, you should still use the set-based version so the trigger does not fail.
The correct way to approach your trigger is as follows:
create or alter trigger [dbo].[StatusChangedUpdateTrigger] on [dbo].[Trans_Order]
after update
as
set nocount on
if ##RowCount=0 return
if Update(OrderStatusId)
begin
update t
set statusChanged=1
from inserted i join deleted d on d.id=i.id and d.OrderStatusId != i.OrderStatusId
join Trans_Order t on t.id=i.id
end
Always test ##rowcount and return if no rows updated.
Always put set options before DML
As you are only looking to update if a specific column is updated you can test specifically for that and if the update statement that's run doesn't touch that column the trigger will not run.
This will correctly account for multiple rows being updated and only update those where the new value is different to the old value.
I have this delete trigger on an SQL database. The record deletes currently and gets written to an audit table. I have been asked to include in this history table a field from another table that is related to the record being deleted based on SurveyID. I thought I could do something like
select #Status = Status from table where Survey = deleted.Survey
But this is incorrect syntax.
ALTER trigger [dbo].[table_Selfdelete]
on [dbo].[table]
after delete
as
Begin
Set nocount on;
Declare #SurveyId int
Declare #StudentUIC varchar(10)
Declare #Status varchar(10)
select #SurveyId = deleted.SurveyID,
#StudentUIC = deleted.StudentUIC
from deleted
select #Status = Status from tbly when SurveyID = deleted.SurveyID
insert into fupSurveyAudit
values(#SurveyId,#StudentUIC,#Status)
End
Arrgh. I think you want this insert in your trigger (and nothing else):
insert into fupSurveyAudit(SurveyId, StudentUIC, status)
select d.SurveyId, d.StudentUIC, y.status
from deleted d left join
tbly y
on d.SurveyId = y.SurveyId;
Notes:
deleted could contain more than one row, so assuming that it has one row can lead to a run-time error or incorrect results.
A left join is needed in case there is no matching row for the status.
You should always include the columns in an insert
Your archive table should have additional columns, such as an identity column and the date of the insert, which are set automatically (and hence not explicitly part of the insert).
Triggers are fired once for each statement (Delete,insert,update) not for each row inside the statement.
You cannot use variables here because when multiple lines are deleted from the table only one line will be inserted in the Audit table because the variable can only hold one value.
You just need a simple insert from the deleted table into the Audit table something like this....
ALTER trigger [dbo].[table_Selfdelete]
on [dbo].[table]
after delete
as
Begin
Set nocount on;
insert into fupSurveyAudit(SurveyId, StudentUIC,[Status])
select d.SurveyID
,d.StudentUIC
,y.[Status]
from deleted d
INNER JOIN tbly y ON y.SurveyID = deleted.SurveyID
End
Try this
ALTER trigger [dbo].[table_Selfdelete]
on [dbo].[table]
after delete
as
Begin
Set nocount on;
insert into fupSurveyAudit -- Better listed the column list here
select
d.SurveyID, d.StudentUIC, y.Status
from
deleted d JOIN tbly y ON d.SurveyID = y.SurveyID
End
O.F.,
So I have been attempting to build a trigger that will update a table based on the when a a row is updated in a different table. The trigger so far looks like this.
ALTER TRIGGER [dbo].[tst_update_USCATVLS_6]
ON [dbo].[IV00101]
AFTER UPDATE
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
DECLARE #ITEMNUMBER VARCHAR(75)
SET #ITEMNUMBER = (SELECT ITEMNMBR FROM dbo.IV00101 WHERE DEX_ROW_TS = (SELECT MAX(DEX_ROW_TS) FROM dbo.IV00101))
UPDATE dbo.EXT00101 SET STRGA255 = (RTRIM(LTRIM(STRGA255))) + '_0' WHERE PT_UD_KEY = #ITEMNUMBER AND PT_UD_Number = 2
What seems to happen when I run the test update like the one below.
UPDATE PDM.TEST.dbo.IV00101
SET USCATVLS_6 = 'OBSOLETE'
WHERE ITEMNMBR = 'HMLGDN-7563252-4'
Is that the trigger fires but updates the desired column twice. The end result being this 20025947756319_0_0 instead of this 20025947756319_0.
The weird part of all of this is if I drop the trigger and run the same test update and then run the update statement that was in the trigger all statements execute and the data is updated as desired.
So running this as one block of code works:
UPDATE PDM.TEST.dbo.IV00101
SET USCATVLS_6 = 'OBSOLETE'
WHERE ITEMNMBR = 'HMLGDN-7563252-4'
DECLARE #ITEMNUMBER VARCHAR(75)
SET #ITEMNUMBER = (SELECT ITEMNMBR FROM PDM.TEST.dbo.IV00101 WHERE DEX_ROW_TS = (SELECT MAX(DEX_ROW_TS) FROM PDM.TEST.dbo.IV00101))
UPDATE PDM.TEST.dbo.EXT00101 SET STRGA255 = (RTRIM(LTRIM(STRGA255))) + '_0' WHERE PT_UD_KEY = #ITEMNUMBER AND PT_UD_Number = 2
If any one can help me figure out why this is happening I would greatly appreciate it.
Kindest regards,
Z.
Having read Sean Lange's Comments I looked up inserted and deleted tables. I saw reference to these tables before but didn't realize they were temporary tables and thought they were physical tables of the database in the example/answers I saw. Anyway I created a trigger to show the data in each which helped me see how to join them to the update statement in the trigger. All the code is below.
Trigger to see what was in Inserted and Deleted as well as the join referencing the Inserted table:
ALTER TRIGGER [dbo].[inserted_deleted_Table]
ON [dbo].[IV00101]
AFTER UPDATE
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
select 'NEW DATA', * from inserted --new data
select 'OLD Data', * from deleted --old data
select 'iv00101', * From iv00101 as i JOIN inserted as u on i.itemNmbr = u.itemNmbr and i.DEX_ROW_TS = u.DEX_ROW_TS
-- Insert statements for trigger here
END
The end solution was to remove this peice of code:
SET #ITEMNUMBER = (SELECT ITEMNMBR FROM INV00101 WHERE DEX_ROW_TS = (SELECT MAX(DEX_ROW_TS) FROM INV00101 ) AND USCATVLS_6 ='OBSOLETE' )
And then Add a the FROM clause to the UPDATE Statement:
UPDATE PDM.TEST.dbo.EXT00101 SET STRGA255 = (RTRIM(LTRIM(STRGA255))) + '_0'
FROM (
SELECT u.ITEMNMBR ,
u.DEX_ROW_TS
From iv00101 as i JOIN inserted as u on i.itemNmbr = u.itemNmbr and i.DEX_ROW_TS = u.DEX_ROW_TS) as p
WHERE PT_UD_KEY = p.ITEMNMBR AND PT_UD_Number = 2
Once I figured out that insert and deleted table were temp tables not actual tables in a DB all the pieces sorta fell into place. Thanks for pointing me in the direction I needed to go #Sean Lange.
Best Regards,
Z.
Well basically I need this trigger to work after a user inserts multiple records into the database. So that when an optionID of 0 is inserted and the IsoptionalID = 1, then set the OptionID = NULL
CREATE TRIGGER ThisDatabase
ON OtherTable
AFTER INSERT
AS
BEGIN
DECLARE #OPTIONID INT
SET #OPTIONID = OtherTable.OPTIONID
DECLARE #ISoptional INT
SET #ISoptional = OtherTable.ISoptional
CASE #optionID WHEN 0 and #ISoptional = 1 set update OtherTable set optionid = null end
END
I am not sure about the case itself either.
Thank you in advance
This depends on the key field(s) of the table, but SQL Server triggers always work on the entire data set being modified (Inserted, Updated, or Deleted). So the trigger would something more like:
CREATE TRIGGER ThisDatabase
ON OtherTable
AFTER INSERT
AS
BEGIN
SET NOCOUNT ON
UPDATE ot
SET ot.OptionID = NULL
FROM OtherTable ot
INNER JOIN INSERTED ins
ON ins.KeyField = ot.KeyField
WHERE ins.OptionID = 0
AND ins.IsOptional = 1
END
The INSERTED table has the rows that were either Inserted or Updated (current version).
The DELETED table has the rows that were either Deleted or Updated (old version).
So, the INSERTED and DELETED tables are pre-filtered to only the changed records, but they are not updatable (since the event already happened due to this being an AFTER trigger and SQL Server not having a BEFORE trigger) so you need to do the UPDATE on the real table.
It isn't really clear what you want to do, but here's a skeleton. Just note:
Triggers are created on the table which is being affected (not an Other table)
You can certainly update another table as a consequence of a trigger. This is typically done through a join.
Use the inserted and deleted pseudo-tables to identify the record(s) which have been inserted, updated or deleted.
CREATE TRIGGER TR_TableBeingInsertedInto
ON TableBeingInsertedInto
AFTER INSERT
AS
BEGIN
UPDATE OtherTable
-- What you actually want to do here isn't clear to me
SET OtherTable.OPTIONID =
CASE i.OptionID
WHEN 0 THEN NULL
ELSE OtherTable.OPTIONID
END
FROM OtherTable
-- Inserted has the same schema as TableBeingInsertedInto
INNER JOIN INSERTED i
ON OtherTable.SomeCommonKey = i.SomeCommonKey;
END
I have an SQL Trigger FOR INSERT, UPDATE I created which basically does the following:
Gets a LineID (PrimaryID for the table) and RegionID From the Inserted table and stores this in INT variables.
It then does a check on joining tables to find what the RegionID should be and if the RegionID is not equal what it should be from the Inserted table, then it should update that record.
CREATE TRIGGER [dbo].[TestTrigger]
ON [dbo].[PurchaseOrderLine]
FOR INSERT, UPDATE
AS
-- Find RegionID and PurchaseOrderLineID
DECLARE #RegionID AS INT
DECLARE #PurchaseOrderLineID AS INT
SELECT #RegionID = RegionID, #PurchaseOrderLineID = PurchaseOrderLineID FROM Inserted
-- Find PurchaserRegionID (if any) for the Inserted Line
DECLARE #PurchaserRegionID AS INT
SELECT #PurchaserRegionID = PurchaserRegionID
FROM
(...
) UpdateRegionTable
WHERE UpdateRegionTable.PurchaseOrderLineID = #PurchaseOrderLineID
-- Check to see if the PurchaserRegionID has a value
IF #PurchaserRegionID IS NOT NULL
BEGIN
-- If PurchaserRegionID has a value, compare it with the current RegionID of the Inserted PurchaseOrderLine, and if not equal then update it
IF #PurchaserRegionID <> #RegionID
BEGIN
UPDATE PurchaseOrderLine
SET RegionID = #PurchaserRegionID
WHERE PurchaseOrderLineID = #PurchaseOrderLineID
END
END
The problem I have is that it is not updating the record and I'm guessing, it is because the record hasn't been inserted yet into the PurchaseOrderLine table and I'm doing an update on that. But can you update the row which will be inserted from the Inserted table?
The major problem with your trigger is that it's written in assumption that you always get only one row in INSERTED virtual table.
SQL Server triggers are statement-triggers not row-triggers. You have to take that fact into consideration.
Now if I understand correctly the logic behind this trigger then you need just one update statement in it
CREATE TRIGGER TestTrigger ON PurchaseOrderLine
FOR INSERT, UPDATE
AS
UPDATE l
SET RegionID = u.PurchaserRegionID
FROM PurchaseOrderLine l JOIN INSERTED i
ON l.PurchaseOrderLineID = i.PurchaseOrderLineID JOIN
(
SELECT PurchaseOrderLineID, PurchaserRegionID
FROM UpdateRegionTable -- !!! change this for your proper subquery
) u ON l.PurchaseOrderLineID = u.PurchaseOrderLineID
For this example I've created a fake table UpdateRegionTable. You have to change it to the proper query that returns PurchaseOrderLineID, PurchaserRegionID (in your code you replaced it with ...). Make sure that it returns all necessary rows, not one.
Here is SQLFiddle demo
I think the problem could be that you are making the update to PurchaceOrderLine inside the trigger that is monitoring updates to the same table as well. Try to alter the trigger to just monitor the inserts, than if this works, you can make some changes or break your trigger on two: one for inserts, another for updates.
This has been resolved. I resolved the problem by adding the trigger to another table as the IF #PurchaserRegionID IS NOT NULL was always false.