declare @userid int --使用者id

declare cur_uid Cursor for select userid from tb_user 
Open cur_uid
Fetch Next From cur_uid into @userid
While(@@Fetch_Status = 0)
Begin
     Begin
		 if(@userid=123456)
		 begin
			 Fetch Next From cur_uid into @userid --continue之前必須Fetch Next，否則會死迴圈
			 continue;
		 end
		 --執行select、insert等業務操作	   
		 --。。。
     End
     Fetch Next From cur_uid into @userid
End
Close cur_uid
Deallocate cur_uid
 

即：

continue之前必須Fetch Next，否則會死迴圈