Convert a Unix timestamp to a DATETIME in a View
the result of the expression 

to_date('1970-01-01','YYYY-MM-DD') + numtodsinterval(1244108886,'SECOND')


is a value of the oracle datatype DATE. This type contains date and time. If you want to display this value to a user you must convert it to a string. This conversion can be done by an application or you can let oracle convert it to a string type as it is done in this example. This automatic conversion to the oracle stringtype VARCHAR2 is controlled by nls_date_format and some server settings. If you want your view to return a VARCHAR2 value with the calculated date in the format 'YYYY-MM-DD HH24:MI:SS' and not a DATE value you can do this by using a conversion function: expression

to_char(to_date('1970-01-01','YYYY-MM-DD') + numtodsinterval(1244108886,'SECOND'),'YYYY-MM-DD HH24:MI:SS')


But in this case the return value of the view is a VARCHAR2 and not a DATE value.