How to implement a column that has a list of history value?

Question

I have implement document library that has a column name called 'Email notification'. A person uploads a document and assign responsibility to another to review it. When s/he assign the email goes to the responsible person. If the responsible person doesn't not complete his/her work. The creator of the document will assign that document again and again till the person complete it. I have setup a workflow that do all the working of sending email and update the column email notification with text 'Email has been sent on "modified date"' i.e. it tells the status of a document. I want this column to store all the dates as a history. Example If I assign a task on 10 October and reassign the same task on 15 October. I should be able to see both dates as a history.
Hope there will be a way to do this.

Many thanks

Answer 1

You can enable versioning on the library. So during each update a new version will get stored.

Another option is to convert the field to Multi Line and enable "Append Changes".

Answer 2

In your workflow, create a Local Variable.

Set that local variable to be all the information you have existing in the column plus the information you need to add.

Once that variable has been updates just set your original field to equal what is in the variable.