删除同一列或连续行的另一列中具有特定值和缺失值的行

Question

我的数据集包含不同公司的每日时间序列，我使用 PostgreSQL。 我的数据集中有一个指标变量，取值 1、-1，大多数情况下为 0。如果指标变量不为 0，并且公司在当天（指标日）或下一天的另一列中有缺失值日，公司将被完全排除在数据集中。

我们可以想到以下示例数据：

date             company   indicator   value
2012-01-02       A         0           2
2012-01-02       B         0           9
2012-01-02       C         0           1
2012-01-02       D         0           3
2012-01-03       A         1           NULL
2012-01-03       B         0           NULL
2012-01-03       C        -1           1
2012-01-03       D         0           2
2012-01-04       A         0           1
2012-01-04       B         0           1
2012-01-04       C         0           NULL
2012-01-04       D         1           4
2012-01-05       A         0           4
2012-01-05       B         0           2
2012-01-05       C         0           1
2012-01-05       D         0           7

因此必须排除 A，因为它在指标日有缺失值，而 C 因为它在指标日的第二天有缺失值。

我尝试了以下方法：

    CREATE TABLE to_delete
    AS SELECT * FROM mytable
    WHERE company IN(
                   SELECT company 
                   FROM mytable 
                   WHERE date BETWEEN (SELECT date FROM mytable WHERE indicator != 0)
                          AND (SELECT date+1 FROM mytable WHERE indicator != 0) 
                   AND indicator != 0)
    AND date BETWEEN (SELECT date FROM mytable WHERE indicator != 0)
                 AND (SELECT date+1 FROM mytable WHERE indicator != 0) 

    DELETE FROM mytable WHERE company in (SELECT DISTINCT company FROM to_delete);

如果示例数据集中仅存在一个不等于零的指标值，则该方法有效。如果不止一个，PostgreSQL 会返回一个错误，说我的子查询返回了不止一行。

我真的很难解决这个问题。您是否知道解决方案，或者可能是实现所需结果的完全其他方法？

Answer 1

我会在很大程度上简化为EXISTS semi-join。

只删除违规行

SELECT * FROM tbl t
-- DELETE FROM tbl t
WHERE  indicator <> 0
AND EXISTS (
   SELECT 1
   FROM   tbl t1
   WHERE  day IN (t.day, t.day + 1)
   AND    t1.company = t.company
   AND    t1.value IS NULL
   )

-> SQLfiddle

使用列名day 而不是date，因为我从不使用基本类型名称作为标识符。

day + 1 在day 属于data type date 时有效（应该如此）。

删除整个公司

公司应完全从数据集中排除。

DELETE FROM tbl t
USING (
    SELECT DISTINCT company
    FROM   tbl t
    WHERE  indicator <> 0
    AND EXISTS (
        SELECT 1
        FROM   tbl t1
        WHERE  day IN (t.day, t.day + 1)
        AND    t1.company = t.company
        AND    t1.value IS NULL
        )
    ) del
WHERE t.company = del.company

-> SQLfiddle

Answer 2

DELETE FROM test WHERE company IN (
WITH 
    for_check AS (SELECT date, company FROM test WHERE indicator != 0)
SELECT test.company 
FROM test 
INNER JOIN for_check fc 
    ON test.date IN (fc.date, fc.date + 1) 
        AND fc.company = test.company 
WHERE test.value IS NULL
)