Question

I need store multiple currencies on my database… Here’s the problem:

Example Tables:

[ Products ]
id (INT, PK)
name (VARCHAR)
price (DECIMAL)
currency (INT, FK)

[ Currencies ]
id (INT, PK)
name (VARCHAR)
conversion (DECIMAL) # To U$

I’ll store the product price with the currency selected by the user…

Later I need to search the products using a price interval like “Search products > with price from U$ 50 to U$ 100” and I need the system convert these values “on the fly” to run the SQL Query and filter the products.

And I really don’t know how to make this query… :/

Maybe something like this?

SELECT p.`name`, p.`price` * c.`conversion` AS price
FROM `products` AS p
INNER JOIN `conversion` AS c
   ON p.`currency` = c.`id`
WHERE price >= 50 AND price <= 100
LIMIT 10

Answer 1

SELECT P.name, P.price local_price, P.price * C.conversion usd_price
FROM   Products P
INNER JOIN Currencies C
ON     C.id = P.currency

And then you can add a condition like

WHERE (P.price * C.conversion) > 50

for prices higher than $50.

EDIT

In case you don’t have one, it’s a good idea to have a currency record for USD (where the conversion value is 1.0), so that conversions to USD are not exceptions.