I have two tables, one called Season the other one Episode. Between them is a Link table that stores SeasonID and EpisodeID. How do I make sure that when a new episode is added the Link table will be updated as well?
Assuming that you are using SQL Service.
We can achieve with the help of trigger like this
Query
CREATE TRIGGER trig_Update_Episode
ON [Episode]
FOR INSERT
AS
Begin
IF NOT EXISTS (SELECT 1
FROM [dbo].[tblEpisodeSession] WITH (NOLOCK)
WHERE [EpisodeId] = [inserted.ID])
PRINT N'You must update an entry in tblSessionEpisode As well';
End
for both the table you should create a trigger like given above.
In example query you can replace message with your actual query which should actually create an entry in tblEpisodeSession.
Hope this helps.
Related
I’m trying to create a trigger to change the value of a column in table B if it finds the information in a column in table A.
An example of my database is below:
[TableA],
itemID
[TableB],
itemID
itemInStock
Once a user creates an entry in Table A declaring an itemID, the trigger needs to change the TableB.itemInStock column to ‘Yes’
I’m still learning SQL so excuse me if I’ve missed something, let me know if you need any more info.
I understand there are better ways of doing this but I've been told I need to do this using a trigger.
I've attempted a few different things, but as it stands nothing is working, below is the current solution I have however this updates all itemInStock rows to 'Yes', where as I only want the ones to update where the TableB.itemID matches the itemID entered in TableA.
ALTER TRIGGER [itemAvailability] ON [dbo].[TableA] FOR
INSERT
AS
BEGIN
UPDATE [dbo].[TableB] set itemInStock = 'Yes' WHERE
TableB.itemID = itemID
END
Two problems -
you're not looking at the Inserted pseudo table which contains the
newly inserted rows
you're assuming the trigger is called once per row - this is not the
case, the trigger is called once per statement and the Inserted
pseudo table will contain multiple rows - and you need to deal with
that
So, your code should look like this -
ALTER TRIGGER [itemAvailability] ON [dbo].[TableA]
FOR INSERT
AS
UPDATE TB
SET itemInStock = 'Yes'
FROM [dbo].[TableB] TB JOIN inserted I
on TB.itemID = I.itemID
I am very new to SQL and SQL server, would appreciate any help with the following problem.
I am trying to update a share price table with new prices.
The table has three columns: share code, date, price.
The share code + date = PK
As you can imagine, if you have thousands of share codes and 10 years' data for each, the table can get very big. So I have created a separate table called a share ID table, and use a share ID instead in the first table (I was reliably informed this would speed up the query, as searching by integer is faster than string).
So, to summarise, I have two tables as follows:
Table 1 = Share_code_ID (int), Date, Price
Table 2 = Share_code_ID (int), Share_name (string)
So let's say I want to update the table/s with today's price for share ZZZ. I need to:
Look for the Share_code_ID corresponding to 'ZZZ' in table 2
If it is found, update table 1 with the new price for that date, using the Share_code_ID I just found
If the Share_code_ID is not found, update both tables
Let's ignore for now how the Share_code_ID is generated for a new code, I'll worry about that later.
I'm trying to use a merge query loosely based on the following structure, but have no idea what I am doing:
MERGE INTO [Table 1]
USING (VALUES (1,23-May-2013,1000)) AS SOURCE (Share_code_ID,Date,Price)
{ SEEMS LIKE THERE SHOULD BE AN INNER JOIN HERE OR SOMETHING }
ON Table 2 = 'ZZZ'
WHEN MATCHED THEN UPDATE SET Table 1.Price = 1000
WHEN NOT MATCHED THEN INSERT { TO BOTH TABLES }
Any help would be appreciated.
http://msdn.microsoft.com/library/bb510625(v=sql.100).aspx
You use Table1 for target table and Table2 for source table
You want to do action, when given ID is not found in Table2 - in the source table
In the documentation, that you had read already, that corresponds to the clause
WHEN NOT MATCHED BY SOURCE ... THEN <merge_matched>
and the latter corresponds to
<merge_matched>::=
{ UPDATE SET <set_clause> | DELETE }
Ergo, you cannot insert into source-table there.
You could use triggers for auto-insertion, when you insert something in Table1, but that will not be able to insert proper Shared_Name - trigger just won't know it.
So you have two options i guess.
1) make T-SQL code block - look for Stored Procedures. I think there also is a construct to execute anonymous code block in MS SQ, like EXECUTE BLOCK command in Firebird SQL Server, but i don't know it for sure.
2) create updatable SQL VIEW, joining Table1 and Table2 to show last most current date, so that when you insert a row in this view the view's on-insert trigger would actually insert rows to both tables. And when you would update the data in the view, the on-update trigger would modify the data.
I have two tables in Filemaker:
tableA (which includes fields idA (e.g. a123), date, price) and
tableB (which includes fields idB (e.g. b123), date, price).
How can I create a new table, tableC, with field id, populated with both idA and idB, (with the other fields being used for calculations on the combined data of both tables)?
The only way is to script it (for repeating uses) or do it 'manually', if this is an ad-hoc process. Details depend on the situation, so please clarify.
Update: Sorry, I actually forgot about the question. I assume the ID fields do not overlap even across tables and you do not need to add the same record more than once, but update it instead. In such a case the simplest script would be like that:
Set Variable[ $self, Get( FileName ) ]
Import Records[ $self, Table A -> Table C, sync on ID, update and add new ]
Import Records[ $self, Table B -> Table C, sync on ID, update and add new ]
The Import Records step is managed via rather elaborate dialog, but the idea is that you import from the same file (you can just type file:<YourFileName> there), the format is FileMaker Pro, and then set the field mapping. Make sure to choose the Update matching records and Add remaining records options and select the ID fields as key files to sync by.
It would be a FileMaker script. It could be run as a script trigger, but then it's not going to be seamless to the user. Your best bet is to create the tables, then just run the script as needed (manually) to build Table C. If you have FileMaker Server, you could schedule this script to be run periodically to keep Table C up-to-date.
Maybe you can use the select into statement.
I'm unsure if you wish to use calculated field from TableA and TableB or if your intension was to only calculate fields from the same table?
If tableA.IdA exists also in tableB.IdA, you could join the two tables and select into.
Else, you run the statement once for each table.
Select into statement
Select tableA.IdA, tableA.field1A, tableA.field2A, tableA.field1A * tableB.field2A
into New_Table from tableA
Edit: missed the part where you mentioned FileMaker.
But maybe you could script this on the db and just drop the table.
Currently I have a Item table and a ItemWaste table.
Both tables will have some fields, such as: Name, Amount, etc. But the ItemWaste table will have one more field, which is the TimeWasted.
I wish to automatically insert the DELETED item from the Item table to the ItemWaste table, and at the same time insert the deletion time to the TimeWasted field.
I got no idea how to do this, is it using trigger???
Hope can get some help here... Appreciate any feedback... Thanks....
Sure - not a problem.
You need a basic AFTER DELETE trigger - something like this:
CREATE TRIGGER trg_ItemDelete
ON dbo.Item
AFTER DELETE
AS
INSERT INTO dbo.ItemWaste(Name, Amount, TimeWasted)
SELECT d.Name, d.Amount, GETDATE()
FROM Deleted d
That's all there is! One point to remember: the trigger is called once per batch - e.g. if you delete 100 rows at once, it will be called once and the pseudo table Deleted will contain 100 rows. The trigger is not called once per row (a common misconception).
Yes, simply by writting a trigger you can insert a row when an delete action is performed in another table, have a look at Triggers
Ok I have a question and it is probably very easy but I can not find the solution.
I have 3 tables plus one main tbl.
tbl_1 - tbl_1Name_id
tbl_2- tbl_2Name_id
tbl_3 - tbl_3Name_id
I want to connect the Name_id fields to the main tbl fields below.
main_tbl
___________
tbl_1Name_id
tbl_2Name_id
tbl_3Name_id
Main tbl has a Unique Key for these fields and in the other table, fields they are normal fields NOT NULL.
What I would like to do is that any time when the record is entered in tbl_1, tbl_2 or tbl_3, the value from the main table shows in that field, or other way.
Also I have the relationship Many to one, one being the main tbl of course.
I have a feeling this should be very simple but can not get it to work.
Take a look at SQL Server triggers. This will allow you to perform an action when a record is inserted into any one of those tables.
If you provide some more information like:
An example of an insert
The resulting change you would like
to see as a result of that insert
I can try and give you some more details.
UPDATE
Based on your new comments I suspect that you are working with a denormalized database schema. Below is how I would suggest you structure your tables in the Employee-Medical visit scenario you discussed:
Employee
--------
EmployeeId
fName
lName
EmployeeMedicalVisit
--------------------
VisitId
EmployeeId
Date
Cost
Some important things:
Note that I am not entering the
employees name into the
EmployeeMedicalVisit table, just the EmployeeId. This
helps to maintain data integrity and
complies with First Normal Form
You should read up on 1st, 2nd and
3rd normal forms. Database
normalization is a very imporant
subject and it will make your life
easier if you can grasp them.
With the above structure, when an employee visited a medical office you would insert a record into EmployeeMedicalVisit. To select all medical visits for an employee you would use the query below:
SELECT e.fName, e.lName
FROM Employee e
INNER JOIN EmployeeMedicalVisit as emv
ON e.EployeeId = emv.EmployeeId
Hope this helps!
Here is a sample trigger that may show you waht you need to have:
Create trigger mytabletrigger ON mytable
For INSERT
AS
INSERT MYOTHERTABLE (MytableId, insertdate)
select mytableid, getdate() from inserted
In a trigger you have two psuedotables available, inserted and deleted. The inserted table constains the data that is being inserted into the table you have the trigger on including any autogenerated id. That is how you get the data to the other table assuming you don't need other data at the same time. YOu can get other data from system stored procuders or joins to other tables but not from a form in the application.
If you do need other data that isn't available in a trigger (such as other values from a form, then you need to write a sttored procedure to insert to one table and return the id value through an output clause or using scope_identity() and then use that data to build the insert for the next table.