Specifies the alias for the implicit database declaration
    executed by the CREATE DATABASE statement. An alias is a name for
    a particular attach to a database that identifies that database
    in subsequent SQL statements.

                                   NOTE

       If you attach to a database using an alias, you must use
       that alias in subsequent statements to qualify the names of
       elements in that database.

    If you omit the FILENAME argument from the database root file
    parameters, SQL also uses the alias as the file name for the
    database root file and creates the root file in the current
    default directory. (SQL generates a syntax error if you include
    a disk or directory specification in the alias clause.) You must
    specify either the FILENAME or alias argument.

    Schema elements in the CREATE DATABASE statement do not need to
    use the alias, however, they cannot specify any other alias.

    The alias clause is optional. The default alias in interactive
    SQL and in precompiled programs is RDB$DBHANDLE. In the SQL
    module language, the default is the alias specified in the
    module header. Using the default alias (either by specifying
    it explicitly in the ALIAS clause or omitting the ALIAS clause)
    declares the database as the default database. Specifying a
    default database means that statements outside the CREATE
    DATABASE statement that refer to the default database do not
    need to use an alias.

    If a default database was already declared, and you specify the
    default alias in the ALIAS clause (or specify any alias that was
    already declared), the results depend on the environment in which
    you issue the CREATE DATABASE statement.

    o  In interactive SQL, you receive a prompt asking if you want
       to override the default database declaration. Unless you
       explicitly override the default declaration, the CREATE
       DATABASE statement fails.

       SQL> -- Assume a default database has been declared:
       SQL> --
       SQL> -- Now create a database without an alias.
       SQL> -- SQL asks if you want to override the default:
       SQL> CREATE DATABASE FILENAME test;
       This alias has already been declared.
       Would you like to override this declaration (No)? NO
       %SQL-F-DEFDBDEC, A database has already been declared with the default
       alias

    o  In embedded SQL or in the SQL module language, specifying
       an already-declared alias in the CREATE DATABASE statement
       generates an error when you precompile the program or compile
       the module.

    o  In dynamic SQL, specifying an already-declared alias overrides
       the earlier declaration.

    For more information about default databases, see the User_
    Supplied_Names HELP topic.