Question

I’ve got a trigger attached to a table.

ALTER TRIGGER [dbo].[UpdateUniqueSubjectAfterInsertUpdate]
   ON  [dbo].[Contents]
   AFTER INSERT,UPDATE
AS
BEGIN

-- Grab the Id of the row just inserted/updated
DECLARE @Id INT

SELECT @Id = Id
FROM INSERTED

END

Every time a new entry is inserted or modified, I wish to update a single field (in this table). For the sake of this question, imagine i’m updating a LastModifiedOn (datetime) field.

Ok, so what i’ve got is a batch insert thingy..

INSERT INTO [dbo].[Contents]
SELECT Id, a, b, c, d, YouDontKnowMe
FROM [dbo].[CrapTable]

Now all the rows are correctly inserted. The LastModifiedOn field defaults to null. So all the entries for this are null — EXCEPT the first row.

Does this mean that the trigger is NOT called for each row that is inserted into the table, but once AFTER the insert query is finished, ie. ALL the rows are inserted? Which mean, the INSERTED table (in the trigger) has not one, but ‘n’ number of rows?!

If so .. er.. 🙁 Would that mean i would need a cursor in this trigger? (if i need to do some unique logic to each single row, which i do currently).

?

UPDATE

I’ll add the full trigger code, to see if it’s possible to do it without a cursor.

BEGIN
    SET NOCOUNT ON

    DECLARE @ContentId INTEGER,
        @ContentTypeId TINYINT,
        @UniqueSubject NVARCHAR(200),
        @NumberFound INTEGER
    
    -- Grab the Id. Also, convert the subject to a (first pass, untested)
    -- unique subject.
    -- NOTE: ToUriCleanText just replaces bad uri chars with a ''. 
    --   eg. an '#' -> ''
    SELECT @ContentId = ContentId, @ContentTypeId = ContentTypeId, 
        @UniqueSubject = [dbo].[ToUriCleanText]([Subject])
    FROM INSERTED
    
    -- Find out how many items we have, for these two keys.
    SELECT @NumberFound = COUNT(ContentId)
    FROM [dbo].[Contents]
    WHERE ContentId = @ContentId
        AND UniqueSubject = @UniqueSubject
    
    -- If we have at least one identical subject, then we need to make it 
    -- unique by appending the current found number.
    -- Eg. The first instance has no number. 
    --     Second instance has subject + '1',
    --     Third instance has subject + '2', etc...
    IF @NumberFound > 0
        SET @UniqueSubject = @UniqueSubject + CAST(@NumberFound AS NVARCHAR(10))

    -- Now save this change.
    UPDATE [dbo].[Contents]
    SET UniqueSubject = @UniqueSubject
    WHERE ContentId = @ContentId
END

Answer 1

Why not change the trigger to deal with multiple rows?
No cursor or loops needed: it’s the whole point of SQL …

UPDATE
    dbo.SomeTable
SET
    LastModifiedOn = GETDATE()
WHERE
    EXIST (SELECT * FROM INSERTED I WHERE I.[ID] = dbo.SomeTable.[ID]

Edit: Something like…

INSERT @ATableVariable
    (ContentId, ContentTypeId, UniqueSubject)
SELECT 
    ContentId, ContentTypeId, [dbo].[ToUriCleanText]([Subject])
FROM
    INSERTED

UPDATE
    [dbo].[Contents]
SET
    UniqueSubject + CAST(NumberFound AS NVARCHAR(10))
FROM
    --Your original COUNT feels wrong and/or trivial
    --Do you expect 0, 1 or many rows.
    --Edit2: I assume 0 or 1 because of original WHERE so COUNT(*) will suffice
    -- .. although, this implies an EXISTS could be used but let's keep it closer to OP post
    (
    SELECT ContentId, UniqueSubject, COUNT(*) AS NumberFound
    FROM @ATableVariable
    GROUP BY ContentId, UniqueSubject
    HAVING COUNT(*) > 0
    ) foo
    JOIN
    [dbo].[Contents] C ON C.ContentId = foo.ContentId AND C.UniqueSubject = foo.UniqueSubject

Edit 2: and again with RANKING

UPDATE
    C
SET
    UniqueSubject + CAST(foo.Ranking - 1 AS NVARCHAR(10))
FROM
    (
    SELECT
        ContentId, --not needed? UniqueSubject,
        ROW_NUMBER() OVER (PARTITION BY ContentId ORDER BY UniqueSubject) AS Ranking
    FROM
        @ATableVariable
    ) foo
JOIN
    dbo.Contents C ON C.ContentId = foo.ContentId 
    /* not needed? AND C.UniqueSubject = foo.UniqueSubject */
WHERE
foo.Ranking > 1