如何计算GROUP BY SQL中的特定行

Question

I have an SQL query that joins two similar queries into a single temporary table. I then build a result set from that single temporary table.

Part of the final result set should include count of which rows are "Equities" and "Options". To solve this I added hard coded columns.

A rough/simplified ERD looks like this:

Equities have a hard coded 1 in EquityType column and Options have a hard coded 1 in the OptionType column. By the way, the TH.Type column also contains unique values to distinguish a row from Equity or Option (values will be either 'Equity' or 'Option').

I feel my solution is, at best, a hack; and there has to be better alternative.

My sql is for MySql, but I do not believe the answer is database specific. Here's the sql:

-- step 1 get equities
CREATE TEMPORARY TABLE IF NOT EXISTS PositionDetails AS
    (
    SELECT TH.Id,
        TH.Symbol,
        TH.TransactionDate,
        TH.Type,
        1 AS 'EquityType',
        0 AS 'OptionType',
        TH.State,
        TH.Position,
        TE.Shares AS Units,
        TE.SharePrice AS UnitPrice,
        TE.Commission,
        TE.Action,
        '' AS 'Data',
        0 AS StrikePrice,
        '' AS 'ExtendedType'
    FROM TradeHeader TH 
    LEFT JOIN TradeEquity TE ON TE.TradeId = TH.Id    
    WHERE TH.Type = 'Equity' AND TH.State = 'Open'
    );

-- step 2 get options
CREATE TEMPORARY TABLE IF NOT EXISTS PositionDetails AS
    (
    SELECT TH.Id,
        TH.Symbol,
        TH.TransactionDate,
        TH.Type,
        0 AS 'EquityType',
        1 AS 'OptionType',        
        TH.State,
        TH.Position,
        TOP.Contracts AS Units,
        TOP.UnitPrice,
        TOP.Commission,
        TOP.Action,
        TOP.ExpirationDate AS 'Data',
        TOP.StrikePrice AS StrikePrice,
        TOP.OptionType AS 'ExtendedType'
    FROM TradeHeader TH
    LEFT JOIN TradeOption TOP ON TOP.TradeId = TH.Id
    WHERE TH.Type = 'Option' AND TH.State = 'Open'
    );

-- step 3 summarize the data    
SELECT 
    PD.Symbol    
  , MIN(PD.TransactionDate) AS FirstTrans
  , MAX(PD.TransactionDate) AS MostRecentTrans
  , SUM((PD.Units * PD.UnitPrice) + PD.Commission) AS Cost
  , COUNT(PD.Symbol) AS Transactions
  , SUM(PD.EquityType) As EquityTrades
  , Sum(PD.OptionType) AS OptionTrades
FROM PositionDetails PD 
GROUP BY PD.Symbol
ORDER BY PD.Symbol;

My question is: how can I get the values for EquityTrades in step 3, without the hardcoded columns I added in my SQL statements step 1 and step 2.

eg, these columns:

0 AS 'EquityType',
1 AS 'OptionType', 

Thnx, Matt

EDIT Updated SQL below:

CREATE TEMPORARY TABLE IF NOT EXISTS PositionDetails AS
    (
    SELECT 
        TH.Id
      , TH.Symbol
      , TH.TransactionDate
      , TH.Type
      , TH.State
      , TH.Position
      , TE.Shares AS Units
      , TE.SharePrice AS UnitPrice
      , TE.Commission
      , TE.Action
      , '' AS 'Data'
      , 0 AS StrikePrice
      , '' AS 'ExtendedType'
    FROM TradeHeader TH 
    LEFT JOIN TradeEquity TE ON TE.TradeId = TH.Id    
    WHERE TH.Type = 'Equity' AND TH.State = 'Open'
    );

INSERT INTO PositionDetails 

    SELECT 
        TH.Id
      , TH.Symbol
      , TH.TransactionDate
      , TH.Type
      , TH.State
      , TH.Position
      , TOP.Contracts AS Units
      , TOP.UnitPrice
      , TOP.Commission
      , TOP.Action
      , TOP.ExpirationDate AS 'Data'
      , TOP.StrikePrice AS StrikePrice
      , TOP.OptionType AS 'ExtendedType'    
    FROM TradeHeader TH
    LEFT JOIN TradeOption TOP ON TOP.TradeId = TH.Id
    WHERE TH.Type = 'Option' AND TH.State = 'Open'
    ;


SELECT 
    PD.Symbol    
  , MIN(PD.TransactionDate) AS FirstTrans
  , MAX(PD.TransactionDate) AS MostRecentTrans
  , SUM((PD.Units * PD.UnitPrice) + PD.Commission) AS Cost
  , COUNT(PD.Symbol) AS Transactions
  , SUM(PD.Type = 'Equity') As EquityTrades
  , Sum(PD.Type <> 'Equity') AS OptionTrades
FROM PositionDetails PD 
GROUP BY PD.Symbol
ORDER BY PD.Symbol;

Answer 1

To aggregate a union, this is the basic format:

SELECT ..., SUM(subU.someValueField)
FROM (
   ... 
   UNION 
   ...
) AS subU
GROUP BY subU.Xfield, subU.Yfield

Answer 2

Instead of using the EquityType and OptionType columns, just use the Type column.

SUM(type = 'Equity') AS EquityTrades,
SUM(type = 'Option') AS OptionTrades

Your second CREATE TEMPORARY TABLE query should be an INSERT INTO PositionDetails , since the table already exists from the first query.

CREATE TEMPORARY TABLE PositionDetails AS
    (
    SELECT TH.Id,
        TH.Symbol,
        TH.TransactionDate,
        TH.Type,
        TH.State,
        TH.Position,
        TE.Shares AS Units,
        TE.SharePrice AS UnitPrice,
        TE.Commission,
        TE.Action,
        '' AS 'Data',
        0 AS StrikePrice,
        '' AS 'ExtendedType'
    FROM TradeHeader TH 
    LEFT JOIN TradeEquity TE ON TE.TradeId = TH.Id    
    WHERE TH.Type = 'Equity' AND TH.State = 'Open'
    );

INSERT INTO PositionDetails
SELECT TH.Id,
    TH.Symbol,
    TH.TransactionDate,
    TH.Type,
    TH.State,
    TH.Position,
    TOP.Contracts AS Units,
    TOP.UnitPrice,
    TOP.Commission,
    TOP.Action,
    TOP.ExpirationDate AS 'Data',
    TOP.StrikePrice AS StrikePrice,
    TOP.OptionType AS 'ExtendedType'
FROM TradeHeader TH
LEFT JOIN TradeOption TOP ON TOP.TradeId = TH.Id
WHERE TH.Type = 'Option' AND TH.State = 'Open';

SELECT 
    PD.Symbol    
  , MIN(PD.TransactionDate) AS FirstTrans
  , MAX(PD.TransactionDate) AS MostRecentTrans
  , SUM((PD.Units * PD.UnitPrice) + PD.Commission) AS Cost
  , COUNT(*) AS Transactions
  , SUM(PD.Type = 'Equity') As EquityTrades
  , Sum(PD.Type = 'Option') AS OptionTrades
FROM PositionDetails PD 
GROUP BY PD.Symbol
ORDER BY PD.Symbol;