Oracle 中的条件分组依据

Question

我正在尝试编写一个查询来获取具有条件的表的总和。例如这张桌子

area    |    machine    |    status    |    qty

1       |    machine1   |    inprocess |    210
1       |    machine2   |    pending   |    120
1       |    machine3   |    done      |    50
2       |    machine1   |    inprocess |    30
2       |    machine2   |    done      |    170

我想要的结果是

area  |  inprocess sum  |  pending sum   | done sum  |  all sum

1     |  210            |  120           | 50        |  380
2     |  30             |  0             | 170       |  200

我正在考虑带条件的 group by 子句，但我似乎无法获得解决此问题所需的解决方案。我试过的是

select distinct 
    area,
    (select sum(qty) from table
     where status = 'inprocess'
     and area = mainTable.area) as inprocess sum
    (select sum(qty) from table
     where status = 'pending'
     and area = mainTable.area) as pending sum
    (select sum(qty) from table
     where status = 'done'
     and are = mainTable.area) as done sum
from table mainTable

在某种程度上，它确实有效，但是当我尝试检查我是否获得了正确的数量时，我似乎无法将实际值与我的查询结果相匹配。（我正在处理一个更大的数据集，数百万条记录）。我想我真正想要的是一个 group by 子句，我可以用它来放置条件，这样它只会聚合与条件匹配的记录。请教绝地大师

Answer 1

您可以尝试使用枢轴查询：

SELECT t.area, SUM(t.isum) AS "inprocess sum",
               SUM(t.psum) AS "pending sum",
               SUM(t.dsum) AS "done sum",
               SUM(t.isum) + SUM(t.psum) + SUM(t.dsum) AS "all sum"
FROM
(
    SELECT area,
        CASE WHEN status = 'inprocess' THEN qty ELSE 0 END AS isum,
        CASE WHEN status = 'pending' THEN qty ELSE 0 END AS psum,
        CASE WHEN status = 'done' THEN qty ELSE 0 END AS dsum
    FROM mainTable
) t
GROUP BY t.area

如果您使用的是 Oracle 11g 或更高版本，那么您还可以利用内置PIVOT函数：

SELECT area, isum_qty AS "inprocess sum", psum_qty AS "pending sum", dsum_qty AS "done sum",
    isum_qty + psum_qty + dsum_qty AS "all sum"
FROM
(
    SELECT area, status
    FROM mainTable
)
PIVOT
(
    SUM(qty) AS qty
    FOR status IN ('inprocess' AS "isum", 'pending' AS "psum", 'done' AS "dsum")
)
ORDER BY area ASC;