To expand a bit on perrin's reply, seek into the DBI docs for the section titled "Database Handle Methods", and probe down there quite a ways to find "table_info", "column_info" and the next few methods after that. If it seems kind of complicated, or if you're concerned by the opening statement in that part of the docs:

Warning: This method is experimental and may change.

don't worry -- there's a reasonable alternative using a query to oracle's own "data dictionary" tables. Here's a query that I've used to get something pretty similar to the output of "describe" -- just do your normal "prepare, execute, fetch_row" sequence using this query, and the results will be the list of columns and some of their attributes:

my $sql = "select column_name, data_type, data_length, nullable from a
+ll_tab_columns where table_name = ?";
[download]

(Just have a scalar variable that holds the table name in ALL_CAPS, and provide that variable when you "execute" the prepared statement.) That query might not tell you everything you want to know about the definitions of the columns -- in which case, just consult a good oracle book about how to query for the attributes you want.