+function delete_exchange_rate($rate_id)
+{
+ $sql = "DELETE FROM ".TB_PREF."exchange_rates WHERE id=".db_escape($rate_id);
+ db_query($sql, "could not delete exchange rate $rate_id");
+}
+
+//-----------------------------------------------------------------------------
+// Retrieve exchange rate as of date $date from external source (usually inet)
+//
+// Exchange rate for currency revaluation purposes is defined in FA as home_currency/curr_b ratio i.e.
+//
+// amount [home] = amount [curr] * ex_rate
+//
+function retrieve_exrate($curr_b, $date)
+{
+ global $SysPrefs;
+
+ $xchg_rate_provider = ((isset($SysPrefs->xr_providers) && isset($SysPrefs->dflt_xr_provider))
+ ? $SysPrefs->xr_providers[$SysPrefs->dflt_xr_provider] : 'ECB');
+
+ $rate = hook_retrieve_exrate($curr_b, $date);
+ if (is_numeric($rate))
+ return $rate;
+ return get_extern_rate($curr_b, $xchg_rate_provider, $date);
+}
+//-----------------------------------------------------------------------------
+
+function get_extern_rate($curr_b, $provider = 'ECB', $date)