TO_LOB converts LONG or LONG RAW values in the column long_column to LOB
values. You can apply this function only to a LONG or LONG RAW column, and only in
the select list of a subquery in an INSERT statement.
看官方这段话就恶心死了。
to_lob只能用在insert into table_name select to_lob(column_name) from table_name
单独select to_lob(column_name) from table_name铁定ora-00932.