title: Issues with MIN & MAX when using Case statement
body: <p>I am trying to generate a summary report using various aggregate functions: MIN, MAX, SUM, etc.  The issue I have is when I try to get a MIN and MAX of a field when I am also using the case statement.   I am unable to get the MIN value of a field when I am using the case statement.  I can best explain it with sample data and the sql statement:</p>
  
  <p>Fields: AccountNumber, Symbol, TradeDate, TransactionType, Price, Quantity, Amount
  Table: Trades</p>
  
  <pre><code>AccountNumber, Symbol, TradeDate, TransactionType, Price, Quantity, Amount
  123,"XYZ",1/2/2011,"Buy",15,100,1500
  123,"XYZ",1/2/2011,"Buy",10,50,500
  123,"XYZ",1/2/2011,"Sell",20,100,2000
  456,"ABC",1/3/2011,"Buy",10,20,200
  456,"ABC",1/3/2011,"Buy",15,30,450
  789,"DEF",1/4/2011,"Sell",30,100,3000
  </code></pre>
  
  <p>Query:</p>
  
  <pre><code>SELECT AccountNumber,
         Symbol,
         SUM(case when TransactionType = "Buy" then 1 else 0) as TotalBuys,
         SUM(case when TransactionType = "Sell" then 1 else 0) as TotalSells,
         MIN(case when TransactionType = "Buy" then Price else 0) as MinBuy,
         MAX(case when TransactionType = "Buy" then Price else 0) as MaxBuy,
         MIN(case when TransactionType = "Sell" then Price else 0) as MinSell,
         MAX(case when TransactionType = "Sell" then Price else 0) as MaxSell,
         MIN(Price) as MinPrice,
         MAX(Price) as MaxPrice
    FROM Trades
  Group By AccountNumber, Symbol
  </code></pre>
  
  <p>What I am expecting is the following results:</p>
  
  <pre><code>AccountNumber, Symbol, TotalBuys, TotalSells, MinBuy, MaxBuy, MinSell, MaxSell, MinPrice, MaxPrice
  123,"XYZ",2,1,10,15,20,20,10,20
  456,"ABC",2,0,10,15,0,0,10,15
  789,"DEF",0,1,0,0,30,30,30,30
  </code></pre>
  
  <p>However, I am getting the following results:</p>
  
  <pre><code>AccountNumber, Symbol, TotalBuys, TotalSells, MinBuy, MaxBuy, MinSell, MaxSell, MinPrice, MaxPrice
  123,"XYZ",2,1,**0**,15,**0**,20,**0**,20
  456,"ABC",2,0,10,15,0,0,10,15
  789,"DEF",0,1,0,0,30,30,30,30
  </code></pre>
  
  <p>When there are two different TransactionTypes for each grouping, the Min fields (MinBuy,MinSell, and MinPrice) are coming out as 0 as opposed to what is expected.  What am I doing wrong on the sql statement?  Is there another way to get the desired results?</p>