Specifies the alias for the implicit database attach executed
    by the IMPORT statement. An alias is a name for a particular
    attachment to a database.

    You must specify an alias or a file name. If you omit the WITH
    ALIAS clause, the default alias for the database created by
    the IMPORT statement is RDB$DBHANDLE. If you omit the FILENAME
    argument, the IMPORT statement also uses the alias as the file
    name for the database root file and creates the root file in
    the current default directory. If you omit WITH ALIAS, you must
    specify the FILENAME argument.