sub trigger_db_prepare {
  my ($dbh) = @_;
  $trigger_desc_sql=$dbh->prepare( qq [ desc trigger ] );
  $trigger_view_sql=$dbh->prepare( qq[ select tid_start,tid_end,class.vid,type,description from trigger,class where class.vid=trigger.vid and tid_start<=? and tid_end>=? and type=?]);
  $trigger_view_enable_sql=$dbh->prepare( qq[ select tid_start,tid_end,class.vid,type from trigger,class where class.vid=trigger.vid and tid_start<=? and tid_end>=? and type=? and disable="N"]);
  $trigger_view_vid_sql=$dbh->prepare( qq[ select tid_start,tid_end,class.vid,description from trigger,class where class.vid=trigger.vid and class.vid=?]);
  $trigger_view_tid_sql=$dbh->prepare( qq[ select tid_start,tid_end,class.vid,type,description from trigger,class where class.vid=trigger.vid and tid_start<=? and tid_end>=? ]);
  $trigger_view_all_sql=$dbh->prepare( qq[ select tid_start,tid_end,class.vid,type,description from trigger,class where class.vid=trigger.vid ]);
  $trigger_view_type_sql=$dbh->prepare( qq[ select tid_start,tid_end,class.vid,type,description from trigger,class where class.vid=trigger.vid and type=?]);
  $trigger_exist_sql=$dbh->prepare( qq [ select vid,tid_start,tid_end,type from trigger where vid=? and tid_start<=? and tid_end>=? and type=?]);
  $trigger_add_sql=$dbh->prepare( qq [ insert into trigger(vid,tid_start,tid_end,type) values(?,?,?,?) ]);
  $trigger_delete_vid_sql=$dbh->prepare( qq [ delete from trigger where vid=? ]);
  $trigger_delete_all_sql=$dbh->prepare( qq [ delete from trigger ]);
}