Oracle SQL-在查询中将缺失的日期添加到另一列中的每个唯一值

Question

我正在尝试通过下表在Oracle SQL中进行查询，我的目标是为每个商店添加缺少的天数。

    +------------+-------+-------+
    |    Date    | Store | Sales |
    +------------+-------+-------+
    | 01/01/2018 | A     |    20 |
    | 01/03/2018 | A     |    30 |
    | 01/02/2018 | B     |    10 |
    | 01/03/2018 | B     |    40 |
    | 01/04/2018 | B     |    50 |
    | 01/01/2018 | C     |    20 |
    +------------+-------+-------+

所需输出：

    +------------+-------+-------+
    |    Date    | Store | Sales |
    +------------+-------+-------+
    | 01/01/2018 | A     |    20 |
    | 01/02/2018 | A     |     0 |
    | 01/03/2018 | A     |    30 |
    | 01/04/2018 | A     |     0 |
    | 01/01/2018 | B     |     0 |
    | 01/02/2018 | B     |    10 |
    | 01/03/2018 | B     |    40 |
    | 01/04/2018 | B     |    50 |
    | 01/01/2018 | C     |    20 |
    | 01/02/2018 | C     |     0 |
    | 01/03/2018 | C     |     0 |
    | 01/04/2018 | C     |     0 |
    +------------+-------+-------+

我有4天需要这个SO问题 ，但是我无法使输出看起来像期望的输出。 有任何想法吗？

Answer 1

使用cross join生成行，然后使用left join引入数据：

select s.store, d.date, coalesce(t.sales, 0) as sales
from (select distinct store from t) s cross join
     (select distinct date from t) d left join
     t
     on t.store = s.store and t.date = t.date;

Answer 2

一种选择是加入日历表：

WITH calendar AS (
    SELECT date '2018-01-01' AS "Date" FROM dual UNION ALL
    SELECT date '2018-02-01' FROM dual UNION ALL
    SELECT date '2018-03-01' FROM dual UNION ALL
    SELECT date '2018-04-01' FROM dual
)     

SELECT
    c."Date",
    s.Store,
    COALESCE(t.Sales, 0) AS Sales
FROM calendar c
CROSS JOIN (SELECT DISTINCT Store FROM yourTable) s
LEFT JOIN yourTable t
    ON t."Date" = c."Date" AND t.Store = s.Store;

在这里可能需要使用正式的日历表，因为也许您当前的表数据集不包含您希望出现在最终报告中的所有日期。