Question

示例：

汽车

Number_plate |      Car_Type     |  Year  |Price_day |Price_hours |

   AA8866DG  | Mitsubishi Lancer |  2008  |   $400   |    $60     |  
   BG7677HJ  | Toyota Harrier    |  2010  |   $600   |    $80     |  
   H76868GB  |   Honda Jazz      |  2009  |   $550   |    $50     |

交易

  NumberTransac | Number_plate  |  Discount|  Unit   |  Duration| Members_Id |Total_Price |

        1       |    AA8866DG   |     0    |  Hours  |   8      |    A01     |     0      |
        2       |    AB5536HG   |     0    |  Days   |   2      |    A01     |     0      |
        3       |    BG7677HJ   |     0    |  Days   |   3      |    A03     |     0      |

我想在Transaction表中计算基于total_price的单位数。

IF Unit = Hours Then

  Car.Price_hours * Transaction.Duration

Else If Unit = Days Then

   Car.Price_day * Transaction.Duration
End If

我对如何将该语句翻译成SQL语句感到困惑。

Answer 1

如果您只想计算交易表中的所有总数，请执行此操作;

SELECT SUM(t.Total_Price) AS 'Total'
FROM Transaction AS t

如果您想从汽车表中获取价格，请执行此操作

SELECT CASE Unit
          WHEN 'Hours' THEN t.duration * c.price_hours
          WHEN 'Days' THEN t.duration * c.price_days
       END AS 'Total Cost'
FROM Transaction AS t INNER JOIN
     Cars AS c ON t.Number_plate = c.NumberPlate

Answer 2

检查

SELECT Number_plate,CASE WHEN Unit='Hours' THEN Car.Price_hours * Transaction.Duration ELSE Car.Price_day * Transaction.Duration END AS Total_Price
FROM Car 
INNER JOIN Transaction ON Car.Number_plate=Transaction.Number_plate

计算2个SQL Server之间的表

2 个答案: