添加一个带有SQL导入任务的标志

I am importing a flat file to SQL using import task. During an import task, I can add a column but is there a way I can add some value (like a flag) to that column? This is for the purpose of finding out which file it is. So I am adding a File column but I want to assign a value to it during every import like "Employees for 2016" so I know which file the data came from.I am importing a flat file to SQL using import