Question

我有一个名为ProfitCalculation的程序。这需要三个参数......程序正文如下：

delimiter //

CREATE PROCEDURE ProfitCalculation
     (
        IN   instrument                      INT(20)    , 
        OUT  buy                             float(10,3)  ,
        OUT  sell                            float(10,3)    ,
        OUT  profit                          float(10,3)   
     )
BEGIN 

    SELECT SUM(FldLastTradeQuantity*FldPrice) as total_buy
    INTO   buy                              
    FROM   TblOrders
    WHERE  FldInstrumentID = instrument AND FldBuySell = 'b' AND FldLastTradePrice != 0 AND FldLastTradeQuantity != 0 group by FldInstrumentID;


    SELECT SUM(FldLastTradeQuantity*FldPrice) as total_buy
    INTO   sell                      
    FROM   TblOrders
    WHERE  FldInstrumentID = instrument AND FldBuySell = 's' AND FldLastTradePrice != 0 AND FldLastTradeQuantity != 0 group by FldInstrumentID; 

     profit = sell - buy;  

END
delimiter ;

现在我想计算利润。但它只返回1。请给我一个解决方案，它将返回实际结果。

Answer 1

此过程可以简化为单个SQL查询，这可以帮助您进行调查。

SELECT buy, sell, (sell - buy) profit FROM (
    SELECT 
        SUM(CASE FldBuySell WHEN 'b' THEN FldLastTradeQuantity*FldPrice END) buy,
        SUM(CASE FldBuySell WHEN 's' THEN FldLastTradeQuantity*FldPrice END) sell
    FROM TblOrders
    WHERE FldInstrumentID = instrument AND FldLastTradePrice != 0 
      AND FldLastTradeQuantity != 0
) a;

Answer 2

试试这段代码 -

...
BEGIN

SELECT
  SUM(IF(FldBuySell = 'b', FldLastTradeQuantity * FldPrice, 0)) AS total_buy,
  SUM(IF(FldBuySell = 's', FldLastTradeQuantity * FldPrice, 0)) AS total_sell
  INTO buy, sell
FROM
  TblOrders
WHERE
  FldInstrumentID = instrument
  AND FldLastTradePrice != 0
  AND FldLastTradeQuantity != 0;

SET profit = sell - buy;

END
...

修改

尝试在MySQL Command-Line Tool或其他工具中运行此代码模式并检查结果 -

SET @instrument = 10; SET @buy = NULL; SET @sell = NULL; SET @profit = NULL; CALL ProfitCalculation(@instrument, @buy, @sell, @profit); SELECT @buy, @sell, @profit;

编辑2：

DELIMITER $$ CREATE PROCEDURE test(OUT buy FLOAT(10, 3), OUT sell FLOAT(10, 3), OUT profit FLOAT(10, 3)) BEGIN SELECT 10, 15 INTO buy, sell; -- variant with SELECT INTO SET profit = sell - buy; END$$ DELIMITER ; SET @buy = NULL; SET @sell = NULL; SET @profit = NULL; CALL test(@buy, @sell, @profit); SELECT @buy, @sell, @profit; +------+-------+---------+ | @buy | @sell | @profit | +------+-------+---------+ | 10 | 15 | 5 | +------+-------+---------+

利润不是空。

如何通过两个查询的结果在一个过程中计算

2 个答案: