Table: dc_client_info
Columns: client
windows
gnu_linux
mac_os_x
haiku

Question: Which Mac OSX's GNU/Linux was yes when Windows was no?
SQL: SELECT "mac_os_x" FROM dc_client_info WHERE "gnu_linux" = 'yes' AND "windows" = 'no'

Question: Which Mac OSX had no haiku and a client that was dc++?
SQL: SELECT "mac_os_x" FROM dc_client_info WHERE "haiku" = 'no' AND "client" = 'dc++'

Question: Which GNU/Linux had no haiku and a client of airdc++?
SQL: SELECT "gnu_linux" FROM dc_client_info WHERE "haiku" = 'no' AND "client" = 'airdc++'

Question: Which client had no GNU/Linux?
SQL: SELECT "client" FROM dc_client_info WHERE "gnu_linux" = 'no'