If the AS clause is specified, the name of the result column is
the name specified on the AS clause.
If the AS clause is not specified and a column list is specified
in the correlation clause, the name of the result column is the corresponding
name in the correlation column list.
If neither an AS clause nor a column list in the correlation clause
is specified and the result column is derived only from a single column
(without any functions or operators), then the result column name
is the unqualified name of that column.
If neither an AS clause nor a column list in the correlation clause
is specified and the result column is derived only from a single variable
(without any functions or operators), then the result column name
is the unqualified name of that variable.
If neither an AS clause nor a column list in the correlation
clause is specified and the result column is derived only from a single
pseudo column (without any functions or operators), then the result
column name is the name of that pseudo column.