CREATE TABLE Treatments (date_of_treatment VARCHAR(255), professional_id VARCHAR(255)); CREATE TABLE Professionals (first_name VARCHAR(255), professional_id VARCHAR(255))
List the date of each treatment, together with the first name of the professional who operated it.
    
SQL: SELECT T1.date_of_treatment, T2.first_name FROM Treatments AS T1 JOIN Professionals AS T2 ON T1.professional_id = T2.professional_id