SQL query for the total PnL for each trader, by symbol

I am cleaning up my laptop tonight, preparing to buy a new one... hopefully before this one dies. Today I found something that I had intended to include the other day when I posted this example for calculating sums across two tables: http://www.sqlfingers.com/2014/09/calculate-sum-across-two-tables.html

Just like that example, this was something the same customer needed very quickly after the close, to report the PnL for each trader account, by symbol.  I've trimmed it down a bit, including only the objects necessary to collect the PnL, but here it is: 

   -- first let's create a table for our traders
   CREATE TABLE dbo.Traders (
      TraderID INT IDENTITY(1,1),
      TraderName VARCHAR(45)
   )
   SET IDENTITY_INSERT dbo.Traders ON
   INSERT dbo.Traders (TraderID,TraderName)
   VALUES (10,'John Doe'),
              (11,'Jane Smith');
   SET IDENTITY_INSERT dbo.Traders OFF;

-- now let's create our daily trades table
CREATE TABLE dbo.Trades (
    TraderID INT,
    TradeID INT,
    Symbol VARCHAR(35),
    Volume BIGINT,
    Side CHAR(1)
)
   -- write some trades
   INSERT dbo.Trades (TraderID,TradeID,Symbol,Volume,Side)
   VALUES ( 10,1, 'AAPL', 10000,1),
                 ( 10,2, 'AAPL', 10000,2),
( 10,3, 'AAPL', -10000,2);

   -- check your data
   SELECT * FROM dbo.Trades

Ok.  Let's say closing price is 1.5.  To return the eod(end-of-day) PnL for each trader by symbol, we'd multiply each symbol's net volume by the closing price.  In this case, it's just AAPL:

  -- declarations

   DECLARE 
@price MONEY = 1.5,
@pnl MONEY

   -- collect the @pnl for AAPL
   SELECT @pnl = @price * SUM(Volume) 
   FROM dbo.Trades 
   WHERE Symbol = 'AAPL'

   -- bring it back out for each trader  - in this example we only have one trader... :-).   
   SELECT t1.TraderName, t2.Symbol, @pnl [PnL]
   FROM dbo.Traders t1 INNER JOIN dbo.Trades t2
          ON t1.TraderID = t2.TraderID
   GROUP BY t1.TraderName, t2.Symbol

Your results:

   TraderName   Symbol    PnL     
   John Doe     AAPL   15000.00

There you go.  Nothing too elaborate... just a SQL query for the closing profit and loss for each trader, by symbol.

I've mentioned before that I have virtually lived with the stock market data for almost 20 years. I have miles of tSQL; current, daily and month-to-date statistics, message ratios, PnL, open order reports, clearing... and more.  If any of you are managing trader volumes and pnl, you know what a pain it can be!  I have decided to share some of this, so you may begin seeing more logic like the one above. Let me know if you're looking for something that you don't see. I may have it already, or I can help you put it together.