Triggers created by ERWin

I am using ERWin to create tables and ERWin creates update and insert triggers, apparently to maintain integrity. Are they really needed to maintain integrity? Should I turn off the feature?

Also, here is some code from an insert trigger that ERWin created.



create trigger tI_tblAR on tblAR for INSERT as
/* ERwin Builtin Tue Jul 27 17:31:08 1999 */
/* INSERT trigger on tblAR */
begin
  declare  @numrows int,
           @nullcnt int,
           @validcnt int,
           @errno   int,
           @errmsg  varchar(255)

  select @numrows = @@rowcount
  /* ERwin Builtin Tue Jul 27 17:31:08 1999 */
  /* tblMain R/97 tblAR ON CHILD INSERT RESTRICT */
  if
    /* %ChildFK(" or",update) */
    update(MainID)
  begin
    select @nullcnt = 0
    select @validcnt = count(*)
      from inserted,tblMain
        where
          /* %JoinFKPK(inserted,tblMain) */
          inserted.MainID = tblMain.MainID
    /* %NotnullFK(inserted," is null","select @nullcnt = count(*) from inserted where"," and") */
   
    if @validcnt + @nullcnt != @numrows
    begin
      select @errno  = 30002,
             @errmsg = 'Cannot INSERT tblAR because tblMain does not exist.'
      goto error
    end
  end

  /* ERwin Builtin Tue Jul 27 17:31:08 1999 */
  /* tblARType R/79 tblAR ON CHILD INSERT RESTRICT */
  if
    /* %ChildFK(" or",update) */
    update(ARType)
  begin
    select @nullcnt = 0
    select @validcnt = count(*)
      from inserted,tblARType
        where
          /* %JoinFKPK(inserted,tblARType) */
          inserted.ARType = tblARType.ARType
    /* %NotnullFK(inserted," is null","select @nullcnt = count(*) from inserted where"," and") */

1)What is update(MainID)
2)In the statement, 'from inserted, tblMain', what is inserted? Is it a table?

I can paste the rest of the code for the insert trigger and the update trigger if needed.

Musleh