Interbase, Sql, trigger. Can't really understand how to write a trigger of this kind: I have several tables. Each one has a document type, status and an unique number. One table in which i wish to create a trigger is a table that holds a file i post, a status of posting, a doctype corresponding to a table and a unique number linking to a record in the corresponding table. I want to change document status in the corresponding table based on the unique number to a certain status depending on the post result (status) that i change after posting. How can I do it?
Trigger T1 will be executed after update on TABLE1.
Trigger checks if TABLE1.StatusOfPosting changed to some value and depending on result updates TABLE2.DocumentStatus.
Depending on bussienes logic, maybe you will need and BEFORE DELETE trigger.
CREATE TRIGGER T1 FOR TABLE1 AFTER UPDATE POSITION 0
AS
BEGIN
IF (NEW.StatusOfPosting <> OLD.StatusOfPosting and NEW.StatusOfPosting=1) THEN
UPDATE TABLE2
SET TABLE2.DocumentStatus=1
WHERE TABLE2.UniqueNumber = TABLE1.UniqueNumber;
END
Related
I have a table where the user is able to insert the ID of a Node that corresponds to a title elsewhere in the database. I want this tile to be automatically inserted into the row after the user has chosen the id.
This is my table:
I need to have the "SommerhusNavn" column be automatically filled with values based on the "SommerhusId" inserted.
I am using a third party to handle the CRUD functionality, where the user picks the ID from a dropdown. I already know in which table the title for the ID is located, I'm just not sure how to fill the row with the insert statement. Would I need to run a separate query for this to happen?
Edit:Solution
CREATE TRIGGER [dbo].[BlokeredePerioderInsert]
ON dbo.BlokeredePerioder
AFTER INSERT
AS
BEGIN
SET NOCOUNT ON;
UPDATE BlokeredePerioder SET SommerhusNavn = text FROM umbracoNode AS umbNode
where SommerhusId = umbNode.id
END
GO
Yes, you need to run additional UPDATE query. Let's assume that you have the TitlesTable, with columns ID and Title. Then it should look like:
UPDATE MyTable SET SommerhusNavn = Title FROM TitlesTable AS A
WHERE SommerhusId = A.ID
AND SommerhusNavn IS NOT NULL --not necessary
Perhaps i'm not understanding, but why can't you use send the value across in the initial update?
Can you use a trigger on the database side?
Alternatively, you'll need to send a update across, following the insert.
This is an hypothetical case..
I'm trying to find a good approach to make sure that every value inserted in an specific column col1 of my table mytable has a specific string http:// at the begining of the value.
Example:
I want to insert myprofile into mytable so (after my check condition..) the final value would be http://myprofile
I guess that a good approach could be using a trigger on insert but I didn't find anything concrete yet..
Any ideas?
Thank you.
You can try something like this as a starting point - this is for SQL Server (don't know MySQL well enough to provide that trigger code for you):
-- create the trigger, give it a meaningful name
CREATE TRIGGER PrependHttpPrefix
ON dbo.YourTableName -- it's on a specific table
AFTER INSERT, UPDATE -- it's for a specific operation, or several
AS
BEGIN
-- the newly inserted rows are stored in the "Inserted" pseudo table.
-- It has the exact same structure as your table that this trigger is
-- attached to.
-- SQL Server works in such a way that if the INSERT affected multiple
-- rows, the trigger is called *once* and "Inserted" contains those
-- multiple rows - you need to work with "Inserted" as a multi-row data set
--
-- You need to join the "Inserted" rows to your table (based on the
-- primary key for the table); for those rows newly inserted that
-- **do not** start with "http://" in "YourColumn", you need to set
-- that column value to the fixed text "http:/" plus whatever has been inserted
UPDATE tbl
SET YourColumn = 'http://' + i.YourColumn
FROM dbo.YourTableName tbl
INNER JOIN Inserted i ON tbl.PKColumn = i.PKColumn
WHERE LEFT(i.YourColumn, 7) <> 'http://'
END
I am trying to create a database trigger that will update certain characters in a field for a table when a user inserts data into the table...
Ex.
ID EXCHANGE LEADRT
1 new L-3
2 new 3
3 new 5
So I would want to leave id 1 alone because the format for the LEADRT is correct but ids 2 and 3 are not.
CREATE TRIGGER triggerupdate ON PoleUnits FOR INSERT,
UPDATE AS
if not exists (select * from Poleunits where LEADRT like '%L-%')
update PoleUnits set LEADRT = STUFF (LEADRT, 1, 0,'L-');
Any ideas why I can't get this to work or better suggestions on how to accomplish this?
In insert and update triggers you have access to a specific table called inserted where the rows to be inserted/updated are held. Those are not real tables, they are just logical tables with the same structure as the table on which the trigger fired.
Your current logic works on the original table, thus working with all the existing data, but not with the data you are actually inserting, i.e. it will update everything except the data you actually want updated. Something like this could work:
CREATE TRIGGER triggerupdate ON PoleUnits
FOR INSERT, UPDATE AS
update PoleUnits
set LEADRT = STUFF (PoleUnits.LEADRT, 1, 0,'L-')
from PoleUnits
inner join inserted -- this is basically a self join
on PoleUnits.ID = inserted.ID
where PoleUnits.LEADRT not like '%L-%'
This will only update those rows in PoleUnits that are being inserted, and only if their LEADRT field is not in the L- format.
Suppose I have tables T1 and T2
Columns of T1 -->Value
Columns of T2 -->OldValue NewValue
What I require is a trigger which will insert a record in T2 on updation of T1 , I need to know the old value and new value also , I have never used triggers before , so can any help me with this , how do I go about creating this trigger.Is it possible ,thanks.
Well, you start writing a trigger with CREATE TRIGGER:
CREATE TRIGGER NameOfTheTriggerPlease
…
The table that should trigger the additional action is T1 so the trigger should be defined ON that table:
CREATE TRIGGER T1OnUpdate /* that's just an example,
you can use a different name */
ON T1
…
The action that the trigger should be invoked on is UPDATE and the timing is AFTER the update, so…
CREATE TRIGGER T1OnUpdate
ON T1
AFTER UPDATE
…
Now's the time to introduce the body of the trigger, i.e. the statements that should actually be executed by the trigger. You introduce the body with the AS keyword followed by the statements themselves.
In your case, there would be just one statement, INSERT, which is obvious. What's not so obvious is how we are going to access the old and the new values. Now, SQL Server offers you two virtual tables, INSERTED and DELETED, and you can easily guess that the former contains all the new values and the latter the old ones.
These tables have the same structure as the table the trigger is assigned to, i.e. T1. They only contain rows that were affected by the particular UPDATE statement that invoked the trigger, which means there may be more than one. And that, in turn, means that you need to have some primary key or a unique column (or a set of columns) in your T1 table that you can use in the trigger to match deleted and inserted rows. (In fact, you might also need your T2 table to have a column that would reference the T1's primary key, so you could later establish which row of T1 had which values stored in T2.)
For the purposes of this answer, I'm going to assume that there's a primary key column called PK and a foreign key column of the same name in T2. And the INSERT statement then might look like this:
CREATE TRIGGER T1OnUpdate
ON T1
AFTER UPDATE
AS
INSERT INTO T2 (PK, OldValue, NewValue)
SELECT i.PK, i.Value, d.Value
FROM INSERTED i INNER JOIN DELETED d ON i.PK = d.PK
One last (but not least) thing to remember: the entire CREATE TRIGGER statement should be the only one in the batch, i.e. there should be no statements preceding the CREATE TRIGGER keywords (but you can put comments there) and, likewise, everything after the AS keyword is considered part of the trigger's body (but you can put the GO delimiter to indicate the end of the statement if you are running the script in SQL Server Management Studio, for instance).
Useful reading:
CREATE TRIGGER (Transact-SQL)
I'm not going to build the whole thing for you (no fun, right?) but I can point you in the right direction
create trigger logUpdate
on T1
After update
as
begin
insert into T2...
--here is just an example
select * from deleted --the DELETED table contains the OLD values
select * from inserted --the INSERTED table contains the NEW values
end
remember that DELETED and INSERTED are internal tables that contains old and new values. On a update trigger, they both exist. On a insert trigger, DELETED will be null because there is nothing being delete. Same logic on a delete trigger, the INSERTED will be empty
EDIT:
answering your question: no matter how many fields you update, your DELETED and INSERTED tables you have all the columns of all the rows affected. Of course, if you update only one column, all the other will have the same value on DELETED and INSERTED
create trigger T_UPD_T1
on T1 FOR update
as
insert into T2 select deleted.value, inserted.value from inserted, deleted
I wish to make a trigger but i'm not sure how to grab the data for whatever caused the trigger.
I have a simlpe table.
FooId INT PK NOT NULL IDENTITY
Name VARCHAR(100) NOT NULL
I wish to have a trigger so that when an UPDATE, INSERT or DELETE occurs, i then do the following.
Pseduocode
IF INSERT
Print 'Insert' & Name
ELSE IF UPDATE
Print 'Update' & FooId & Name
ELSE IF DELETE
Print 'Delete' & FooId & Name
Now, I know how to make a trigger for a table.
What i don't know how to do is figure out the values based on what the trigger type is.
Can anyone help?
Edit: Not sure if it helps, but db is Sql Server 2008
the pseudo table "inserted" contains the new data, and "deleted" table contains the old data.
You can do something like
create trigger mytrigger on mytable for insert, update, delete
as
if ( select count(*) from inserted ) > 0
-- insert or update
select FooId, Name from inserted
else
-- delete
select FooId, Name from deleted
To clarify all the comments made by others, on an insert, the inserted table contains data and deleted is empty. On a delete, the situation is reversed. On an update, deleted and inserted contain the "before" and "after" copy of any updated rows.
When you are writing a trigger, you have to account for the fact that your trigger may be called by a statement that effects more than one row at a time.
As others have pointed out, you reference the inserted table to get the values of new values of updated or inserted rows, and you reference the deleted table to get the value of deleted rows.
SQL triggers provide an implicitly-defined table called "inserted" which returns the affected rows, allowing you to do things like
UPDATE mytable SET mytimestamp = GETDATE() WHERE id IN (SELECT id FROM inserted)
Regarding your code sample, you'll want to create separate INSERT, UPDATE and DELETE triggers if you are performing separate actions for each.
(At least, this is the case in SQL Server... you didn't specify a platform.)
On 2008, there is also MERGE command. How do you want to handle it?
Starting from 2008, there are four commands you can modify a table with:
INSERT, UPDATE, DELETE, and MERGE:
http://blogs.conchango.com/davidportas/archive/2007/11/14/SQL-Server-2008-MERGE.aspx
http://sqlblogcasts.com/blogs/grumpyolddba/archive/2009/03/11/reasons-to-move-to-sql-2008-merge.aspx
What do you want your trigger to do when someone issues a MERGE command against your table?