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，取值为1，-1且大部分时间为0.如果指标变量不为0，并且公司在当天（指标日）或下一列中的另一列中缺少值那天，公司应完全被排除在数据集之外。

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，因为它在指标日具有缺失值，而C因为它在指标日后的某一天缺少值。

我尝试了以下内容：

    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);

如果示例数据集中只存在一个不等于零的指标值，则它有效。有多个，PostgreSQL返回一个错误，说我的子查询返回多行。

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

我会用EXISTS semi-join进行简化。

仅删除有问题的行

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。

如果day + 1属于data type date（应该是这样），则

day有效。

删除整个公司

公司应完全被排除在数据集之外。

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
)

删除一列中具有特定值的行，并删除相同或连续行的另一列中的缺失值

2 个答案:

仅删除有问题的行

删除整个公司