Creating a trigger that manipultes a field in SQL Server

Guys, I have a table called tblNames and one of my fi开发者_如何转开发elds in this table is called 'UpFileName'. Is it possible to create an insert trigger that would automatically replace all '%20' in the UpFileName field to underscores '_'?

I'm using SQL Server 2005.

In general it is like this, replace ID with the PK of your table

CREATE TRIGGER  trTriggerName  ON  tblNames   
 AFTER INSERT  AS  
UPDATE tblNames 
   SET UpFileName = replace(UpFileName,'%20','_') 
FROM tblNames t
JOIN INSERTED i ON t.ID = i.ID

However if you don't want people to insert certain types of data then use check constraints. Right now you are doing extra work for every inserts because this trigger fires