Queries :: Concatenate Multiple Records Grouped By Date?

I have a rates table with 3 fields : [RateDate], [CurrencyID], [FXRate]

I also have a currencies table with 2 fields : [CurrencyID], [CurrencyCode]

Where [CurrencyCode] is just the 3-character currency code (i.e. EUR, GBP, USD etc.)

The rates table uses a composite primary key across [RateDate] and [CurrencyID] - i.e., there should only be one unique record for each combination of date and currency.

Not every date will be present in the table and, within each of those dates, not every currency will be present (but at least one, obviously)

I want to write a query which will return two fields. The first field will contain all of the unique dates in the table for which the [FXRate] field (for any currency) is blank / null. Straightforward enough :

Code:
SELECT [tblRates].[RateDate]
FROM [tblRates]
INNER JOIN [tblCurrencies]

[Code]....

But this gives me a separate record for each date / currency combination in the returned dataset. I just want one record per date and all of the currency codes in a single string (separated by some delimiter) as a text field.