There may be times where the user wants to create a filter for a specific column, but that column might not display nicely in the filter dropdown tab. For these cases, a second column can be used as the display name for the filter, while the underlying value remains the same.
If there exists a Users table, it would be useful to have a filter to look up all of a particular user's info. The Users table looks something like this:
Now the filter should display a user's first and last name, and still be able to filter on an individual user. So, filter can be created like so:
Concatenate the first and last names as the display name, and select the id as the value. The filters parse the query, and use the first selected column as the value and the second as the display name.
Now, pick a couple of options from the filter and return to the query to use them. With just two users selected, the query returns all of the information about them, using their underlying id's.
Navigating to the Query tab and viewing the expanded SQL will reveal how Periscope interprets the underlying filter values.