Suppose we have the following database:
Exchange Rate DB
| current_date | sourceCurrency | targetCurrency | exchangeRate |
| Aug 26 10:41:52 EDT 1999 | CAD | USD | 0.665572 |
| Aug 26 10:41:52 EDT 1999 | USD | CAD | 1.50244 |
| Aug 26 10:41:52 EDT 1999 | CAD | EUR | 0.638588 |
| Aug 26 10:41:52 EDT 1999 | EUR | CAD | 1.56601 |
| Aug 26 10:41:52 EDT 1999 | USD | EUR | 1.04229 |
| Aug 26 10:41:52 EDT 1999 | EUR | USD | 0.959446 |
If we want to find an exchange rate, we will have to provide the sourceCurrency and targetCurrency to get perform the query. Hence, the INPUT will be:
<INPUT>
<elementType id="from"> <string/>
</elementType>
<elementType id="to"> <string/>
</elementType>
</INPUT>