SELECT
  currencyExchangeID
INTO
  :currencyExchangeID
FROM
  CurrencyExchange 
WHERE :currencyTypeCode = currencyTypeCode 
  AND :theDate >= rateFromDate 
  AND 
  (
    
    (
      :theDate <= rateToDate 
    ) 
    OR 
    (
      rateToDate IS NULL 
    ) 
  ) 
  AND :statusCode = statusCode