select_item ::=
{
    function_name [(parameter_name [, parameter_name]...)]
  | NULL
  | numeric_literal
  | [schema_name .] {table_name | view_name} . *
  | [[schema_name .] {table_name . | view_name .}] column_name
  | sequence_name . {CURRVAL | NEXTVAL}
  | subquery
  | 'text'
} 
[[AS] alias]