对同一个表中的多个求和列进行 SQL 外连接

Question

我正在使用一个 SQL 库（编程库，符合 ANSI SQL 标准，称为 ABS 数据库，（http://www.componentace.com/help/absdb_manual/absdbmanual_content.htm）。它支持各种联接、CASE 等。 请

我有一个表（appt），它是一个约会表。

ApptKey - Integer - Primary Key
SA_ID -  Integer  (a person’s ID, think employee number),
Layer - Integer – only 4 different values, 1, 2, 3 or 4 (think Appt Category)
Number_Of_Minutes  - Integer – the length of the appointment

注意，某些 SA_ID/层组合可能为空（即该组合没有行）。组合可能有多行（我没有显示其他列，因为它们在这里不相关，我需要一份报告来显示每个人（SA_ID）、每一层、一行的分钟总和……即每个 SA_ID 有他们自己的行，显示 Layer =1 的总和、Layer =2 的总和、Layer =3 的总和以及 Layer = 4 的总和。

示例数据…

SA_ID         LAYER        Number_of_Minutes
1             1            10
1             1            30
2             1            10
3             2            10
1             4            10

我需要一个给出此结果的查询，

SA_ID      LAYER_1     LAYER_2    LAYER_3     LAYER_4
1          40          0          0           10
2          10          0          0           0
3          0           10         0           0

我需要此类型 。格式，因为此查询提供图表/图形组件...

我认为我需要使用多个相关子查询的右连接，但我无法让它工作，这是我下面运行的正确方法，但作为直接连接。我可以（或者如何）重写它以使用右外连接？右外连接是最好的方法吗？

select g.sa_id,  l1.totalsum, l2.totalsum, l3.totalsum, l4.totalsum
from  (select sa_id, layer, sum(number_of_minutes) totalsum from appt where layer = 1 group by sa_id, layer) l1,
           (select sa_id, layer, sum(number_of_minutes) totalsum from appt where layer = 2 group by sa_id, layer) l2,
           (select sa_id, layer, sum(number_of_minutes) totalsum from appt where layer = 3 group by sa_id, layer) l3,
          (select sa_id, layer, sum(number_of_minutes) totalsum from appt where layer = 4 group by sa_id, layer) l4,
          (select distinct sa_id "sa_id" from appt) g
where
      (l1.sa_id = g.sa_id)
and   (l2.sa_id = g.sa_id)
and   (l3.sa_id = g.sa_id)
and   (l4.sa_id = g.sa_id)

Answer 1

SELECT SA_ID,
SUM(CASE WHEN LAYER = 1 THEN Number_of_Minutes ELSE 0 END) AS LAYER_1, 
SUM(CASE WHEN LAYER = 2 THEN Number_of_Minutes ELSE 0 END) AS LAYER_2,
SUM(CASE WHEN LAYER = 3 THEN Number_of_Minutes ELSE 0 END) AS LAYER_3,
SUM(CASE WHEN LAYER = 4 THEN Number_of_Minutes ELSE 0 END) AS LAYER_4
FROM Appt
GROUP BY SA_ID

编辑：因为它支持 CASE 表达式。

Answer 2

SELECT
    t.sa_id,
    Layer1=(SELECT SUM(Number_of_Minutes) FROM appt WHERE sa_id = t.sa_id AND Layer = 1),
    Layer2=(SELECT SUM(Number_of_Minutes) FROM appt WHERE sa_id = t.sa_id AND Layer = 2),
    Layer3=(SELECT SUM(Number_of_Minutes) FROM appt WHERE sa_id = t.sa_id AND Layer = 3),
    Layer4=(SELECT SUM(Number_of_Minutes) FROM appt WHERE sa_id = t.sa_id AND Layer = 4)

FROM
(
    SELECT DISTINCT
        sa_id
    FROM appt
) t