Transform a field to date

Hello,
I have field periodDate in this format: 01/01/2001, day/month/year). How can I transform this field become a date field and apply the year() or quarter() functions?

try going to settings->admin->table metadata and from there click the gear on the specific field. You might be able to transform that field (which I think it's saved as a string right?) to a datetime

Hello,
Yes it's saved as string. They are lot of datetime type, i chose "attach a date". In the editor i do year(dateField) and i get nothing when I preview the result