Question

任务9 每个兽医每天开出的药物总费用是多少？仅显示兽医的ID，访问日期和总费用。按兽医的ID和访问日期对报告进行排序。

这是我得到的输出：

VET_ID  VISIT_DATE  TOTAL_COST
V01     21-Apr-2004 36.49
V01     21-Apr-2004 38.49
V01     21-Apr-2004 41.88
V01     21-Apr-2004 40.24
V01     21-Apr-2004 35.99
V01     21-Apr-2004 35.99
V01     27-Apr-2004 32.5
V01     27-Apr-2004 37.89
V01     27-Apr-2004 32
V01     27-Apr-2004 34.5

SELECT Visit.Vet_id, Visit.Visit_Date, (Basic_Cost + Cost) AS Total_Cost
FROM Visit
INNER JOIN Medication ON Visit.Vet_id = Medication.Vet_id
ORDER BY Vet_ID, Visit_Date;

这是预期的输出：

Vet Date      Total Cost
--- --------- ------------
V01 21-APR-04 12
V01 27-APR-04 16.25
V01 03-MAY-04 26.5
V01 22-JUN-04 30.39
V02 21-APR-04 38.5
V02 28-APR-04 12.5
V02 16-MAY-04 27.5
V03 28-APR-04 7.99
V03 08-MAY-04 7.99
V03 13-MAY-04 28.25
V04 03-MAY-04 10.49
V04 07-MAY-04 16.75
V04 12-MAY-04 46.05
V04 13-MAY-04 22.5
V04 17-MAY-04 32.85
V04 19-MAY-04 17.5

Answer 1

您必须在加入后group by Visit.Vet_id, Visit.Visit_Date才能计算总和：

SELECT 
  Visit.Vet_id, 
  Visit.Visit_Date, 
  SUM(Medication.Basic_Cost + Medication.Cost) AS Total_Cost
FROM Visit INNER JOIN Medication 
ON Visit.Vet_id = Medication.Vet_id
GROUP BY Visit.Vet_id, Visit.Visit_Date
ORDER BY Visit.Vet_id, Visit.Visit_Date;

我猜Basic_Cost和Cost是表Medication中的列，如果未更改为Visit。

Answer 2

您可以在自己的查询中使用子查询。听起来很像。

with grouped as (
    SELECT 
            Visit.Vet_id, 
            Visit.Visit_Date, 
            (Basic_Cost + Cost) AS Total_Cost
    FROM Visit
    INNER JOIN 
        Medication ON Visit.Vet_id = Medication.Vet_id
    ORDER BY Vet_ID, Visit_Date;
)  
    select 
        Vet_id, 
        Visit_Date, 
        sum(Total_Cost) 
    from grouped
    group by 
        Vet_id,Visit_Date

如何唯一显示SQL

2 个答案: