SQL-更新，插入还是代替触发器？

Question

In case of updating or inserting value to one of the fields in my table, I would like to check that the value does not contain some chars. If it does, don't insert nothing. I did this "Instead of" trigger, but it worked only for inserted rows and not for updated rows . What did I do wrong? Did I choose the right trigger for this task?

ALTER TRIGGER trg_MakeSureOfCleanDescription
ON [dbo].[Car]
instead OF INSERT
AS
  BEGIN
      DECLARE @CharPosition_Inserted INT;

      SET @CharPosition_Inserted = 0;

      DECLARE @CharPosition_Updated INT;

      SET @CharPosition_Updated = 0;

      SELECT @CharPosition_Inserted = CHARINDEX('<', inserted.Description)
      FROM   inserted

      --select @CharPosition_Updated = CHARINDEX('<', inserted.Description) from 
      IF( @CharPosition_Inserted = 0/*and @CharPosition_Updated = 0*/ )--only if the description is html free, insert it. Otherwise don't insert nothing.
        BEGIN
            PRINT 'no html. inserting.'

            INSERT INTO Car
                        ([Year],
                         [Make],
                         [Model],
                         [Price],
                         [ExtColor],
                         [IntColor],
                         [Body],
                         [Engine],
                         [Transmission],
                         [Miles],
                         [VIN],
                         [Description],
                         [MainImage],
                         [VideoFile],
                         [StockNumber],
                         [Sold])
            SELECT [Year],
                   [Make],
                   [Model],
                   [Price],
                   [ExtColor],
                   [IntColor],
                   [Body],
                   [Engine],
                   [Transmission],
                   [Miles],
                   [VIN],
                   [Description],
                   [MainImage],
                   [VideoFile],
                   [StockNumber],
                   [Sold]
            FROM   inserted
        END
  END 

Thanks.

My code:

Answer 1

you are only checking for the insert action. The update is treated totally differently and has to be handled in a separate trigger. As there are Before and After triggers for insert, so there are before and after triggers for Update and Delete as well. In your case you need to create another trigger for the update scenario.

https://technet.microsoft.com/en-us/library/ms188601%28v=sql.105%29.aspx