How to build a query that gets its values from a file
If the restriction on creating tables includes "external tables", then you need to get management to lift that restriction.  As stated, you can't expect oracle (or any rdbms product, for that matter) to just magically be able to recognize some external file as a data source and be able to process it with SQL statements.  External tables is how oracle does that.  If you read up on external tables in the oracle docs, you will see that it is not a table that contains data within the database, but simply a description of an external file, and that allows oracle to treat that file as if it were an actual table.