Thank you for your help!I found also another solution.In the "load file" activity I added for each column a "correspondence" :if value = unknown then empty value 

Hello everyone, would you be able to help me to define an expression in an "update data" activity ? I want to import a file containing values equals to "unknown". But for every values = unknown, I want to import an empty value in Adobe Campaign. So I need to create an expression that convert a value...