Microsoft SQL 2005简单触发器如何:编写不更新任何内容的触发器?

对触发器感到困惑:我有两种类型的记录,“L”库和“N”正常。当“N”被更新或插入时,我需要更新相应的“L”。“L”记录的更新不应更新自身。 此代码不允许更新成功。为什么?

ALTER trigger updateProductLibrary
on Product
after update as
BEGIN
    -- either deleted (old) or inserted (new)
    declare @counter int, @insertedType char(1)
    set @insertedType = 'Z'

    select @insertedType = i.type
    from inserted i

    if( @insertedType = 'N')
    begin
        select @counter = count(*)
        from product p join inserted i on
        p.sku = i.sku and
        p.type = 'L' -- for library

        if( @counter > 0) -- update
        BEGIN
            update p set name = i.name
            from product p join inserted i on
                 p.sku = i.sku and
                 p.type = 'L'
        END
        ELSE -- insert
        BEGIN
            insert into product (sku, name, type)
            select  i.sku, i.name, 'L'
            from inserted i
        END
    END
END