I had been trying to get the list of all issues who had been assigned to some one else at some time and changed at present
I had tried this piece of code
assignee was "UserA" and assignee != "UserA"
It would return all issues that this user had previously been assigned.But how can i get all issues from all users.Something similar to this
assignee was "AllUsers" and assignee != "AllUsers"
To get all the issues where the assignee has changed then you could do:
assignee changed
However I don't believe there is a way that you can do a JQL to search for all issues where a user was assigned to it but no longer is short of creating your on JIRA plugin that adds a JQL function.