ident() takes strings and turns them as database identifiers (e.g. table
or column names) quoting them using the identifer rules for your database.
ident_q() does the same, but assumes the names have already been
quoted, preventing them from being quoted again.
These are generally for internal use only; if you need to supply an
table name that is qualified with schema or catalog, or has already been
quoted for some other reason, use I().