Full outer join on one criteria, inner join on another

Question

i need to join Header and Detail rows into one resultset:

(sample DDL and inserts to follow):

Orders:

OrderID  OrderDate                CurrencyID  BuyAmount  BuyRate 
=======  =======================  ==========  =========  ========
1        2011-09-01 15:57:00.000  7           12173.60   1.243893
1        2011-09-01 15:57:00.000  9           69.48      1

OrderDetails:

OrderID  CurrencyID  SellAmount  SellRate
=======  ==========  ==========  ========
1        7           10000       1
1        8           12384       0.9638

i want them joined on OrderID and CurrencyID:

OrderID  CurrencyID  BuyAmount  BuyRate   SellAmount  SellRate
=======  ==========  =========  ========  ==========  ========
1        7           12173.60   1.243893  10000       1
1        8           NULL       NULL      12384       0.9638
1        9           69.48      1         NULL        NULL

Sample scripts

--USE Scratch

--Create a temporary `Orders` and, `OrderDetails` tables:
IF OBJECT_ID('tempdb..#Orders') > 0 DROP TABLE #Orders
CREATE TABLE #Orders
(
    OrderID int NOT NULL,
    OrderDate datetime NOT NULL,
    CurrencyID int NOT NULL,
    BuyAmount money NOT NULL,
    BuyRate real NOT NULL
)

IF OBJECT_ID('tempdb..#OrderDetails') > 0 DROP TABLE #OrderDetails
CREATE TABLE #OrderDetails
(
    OrderID int NOT NULL,
    CurrencyID int NOT NULL,
    SellAmount money NOT NULL,
    SellRate real NOT NULL
)

-- **Insert sample data:**

INSERT INTO #Orders (OrderID, OrderDate, CurrencyID, BuyAmount, BuyRate) 
VALUES (1, '20110901 15:57:00', 7, 12173.60, 1.2438933)
INSERT INTO #Orders (OrderID, OrderDate, CurrencyID, BuyAmount, BuyRate) 
VALUES (1, '20110901 15:57:00', 9, 69.48, 1)


INSERT INTO #OrderDetails (OrderID, CurrencyID, SellAmount, SellRate)
VALUES (1, 7, 10000, 1)
INSERT INTO #OrderDetails (OrderID, CurrencyID, SellAmount, SellRate)
VALUES (1, 8, 12384, 0.9638)


/*Desired Output:
OrderID  CurrencyID  BuyAmount  BuyRate   SellAmount  SellRate
=======  ==========  =========  ========  ==========  ========
1        7           12173.60   1.243893  10000       1
1        8           NULL       NULL      12384       0.9638
1        9           69.48      1         NULL        NULL

*/

i can't find a combination of RIGHT OUTER JOIN, FULL OUTER JOIN, COALESCE that can produce my desired output.

---

Update:

It's also possible that OrderDetails doesn't contain a matching CurrencyID from the Orders table:

Orders:

OrderID  CurrencyID  BuyAmount  BuyRate 
=======  ==========  =========  ========
1        7           12173.60   1.243893
1        9           69.48      1

OrderDetails:

OrderID  CurrencyID  SellAmount  SellRate
=======  ==========  ==========  ========
1        8           12384       0.9638

Answer 1

So, you've tried this?

SELECT
  COALESCE(o.OrderID, od.OrderID) AS OrderID,
  COALESCE(o.CurrencyID, od.CurrencyID) AS CurrencyID,
  o.BuyAmount,
  o.BuyRate,
  od.SellAmount,
  od.SellRate
FROM
  #Orders AS o
  FULL OUTER JOIN #OrderDetails AS od
    ON o.OrderID = od.OrderID
    AND o.CurrencyID = od.CurrencyID

Answer 2

SELECT od.OrderID, od.CurrencyID, o.BuyAmount, o.BuyRate, od.SellAmount, od.SellRate
    FROM #OrderDetails od
        LEFT JOIN #Orders o
            ON od.OrderID = o.OrderID
                AND od.CurrencyID = o.CurrencyID