If statements in SQL

To have a conditional statement in a SELECT statement, use CASE WHEN…THEN….ELSE.

create view logbook as
        select  "Date",
                "N Number",
                "From","To",
                "Number of Instrument Approaches",
                "Number of Night Landings",
                "Total Flight Duration" - "Night" as "Day",
                "Night",
                "Simulator",
                "Simulated Instrument",
                "Actual Instrument",
                 case when "IsCrossCountry" = true  then "Total Flight Duration"  else 0.0 end as "Cross Country"
         from flights;